TX 

IM7; 

904 



U. S. DEPARTMENT OF AGRICULTURE. 

OFFICE OF EXPERIMENT STATIONS— BULLETIN NO. 143. 
A. c. TRUE, Director. 



STUDIES 



DIGESTIBILITY AND NUTRITIVE VALUE OF BREAD 



MAIXE AGRICULTUEAL EXPERIMENT STATIOX 



1 8 Q 0-1 Q03 



O. D. wo< ;)DS, 

Director, Main, Agricultural Eocpmment Station, 

AXD 

L. EL MEERILL, 
Chemist, Maine Agricultural Experinf nl Station. 




WASHINGTON: 

GOVERNMENT PRINTING OJFFICB; 

1904. 




Qass _Z ] 

Book 2iL 



3t<>- 



U. S. DEPARTMENT OF AGRICULTURE. 

f 

OFFICE OF EXPERIMENT STATIONS— BULLETIN NO. 143. 

A. C. TRUE, Director. 



STUDIES 



6~ v a 



DIGESTIBILITY AND NUTRITIVE VALUE OF BREAD 

AT THE 

MAINE AGRICULTURAL EXPERIMENT STATION 



1 SQ 9-1 Q03 



C. D. WOODS, 
Director, Maine Agricultural Experiment Station, 

AND 

L. H. MERRILL. 
Chemist, Maine Agricultural Experiment Station. 




WASHINGTON: 

GOVERNMENT PRINTING OFFICE, 
L904. 






rx 






OFFICE OF EXPERIMENT STATIONS. 

A. ('. True, Ph. P.. Director. 

E. W. Ai. i, en, I'h. I>., Assistant Director and Editor of Experiment Station Record. 

C. F. Langwortiiy, I'h. 1>.. Editor and Expert on Foods and Annual Production. 

NUTRITION INVESTIGATIONS. 

W. <). Atwater, Ph. D., Cltief of Nutrition Investigations, Middletotm, (••„„ 

C. P. Woods, B. S., Special Agent »i Orono, V- . 

1''. <i. Benedict, Ph. I'.. Physiological Chemist, Middletown, Conn. 

R. P. Milner, Ph. J'.., Editorial Assistant, Middletown, ''om,. 






LETTER OF TRANSMITTAL 



U. S. Department of A<;kktxtuee. 

Offke of Experiment Stations. 
Washington, D. < '., February 15, 1904. 
Sir: I have the honor To transmit herewith and to recommend for 
publication as a bulletin of this Office a report of investigations on 
the digestibility and nutritive value of bread and on methods of sepa- 
rating feces in digestion experiments with man. carried on at the 
Maine Agricultural Experiment Station in 1899-1903, by Charles D. 
Wood-, director, and L. H. Merrill, chemist of the station. The 
studies were conducted under the immediate supervision of Prof. 
W. O. Atwater. chief of nutrition investigations, and form a part of 
the investigations on the food of man conducted under the auspices 
of this Office. 

The results of the digestion experiments with bread made from 
different sorts of flour ground from the same Lots of wheat are in 
accord with those obtained in earlier investigations of this series, and 
show that breads made from all the common grades of flour are quite 
thoroughly digested and differ little in nutritive value. They also 
emphasize the fact that breads of all sorts are among the most useful 
and economical articles of diet. 

Respectfully, A. 0. Trie. 

Director. 
Hon. James Wilson, 

St '/■' tary of u Vgrhcultiwrt . 



CONTEXTS. 



Page. 

Introduction 7 

Experiments on the digestibility i >f 1 tread 9 

Description of flours . . 10 

Preparation of the food _ , 11 

Separation of feces 12 

Collection of urine 13 

Analyses of foods and excretory products 13 

Composition of food materials 14 

Composition of feces . 15 

Statistics of urine 16 

Details of digestion experiments Nos. 431-441 19 

Digestion experiment No. 431 21 

I 'igestion experiment No. 432 22 

Digestion experiment X< >. 433 23 

Digestion experiment N< >. 434 24 

I Hgestion experiment N< >. 435 25 

Digestion experiment No. 436 26 

Digestion experiment N< >. 437 27 

Digestion experiment X< >. 438 28 

Digestion experiment N< >. 439 29 

Digestion experiment N< >. 440 30 

Digestion experiment N< <. 441 . . ; 31 

Summary of results 31 

Details < »f digestion experiments Nos. 442—150 34 

Digestion experiment No. 442 35 

Digestion experiment No. 443 36 

Digestion experiment No. 444 37 

Digestion experiment No. 445 37 

Digestion experiment No. 446 38 

Digestion experiment No. 447 _ 39 

Digestion experiment No. 448 39 

1 digestion experiment No. 449 40 

I (igestion experiment No. 450 41 

Summary of results _ 41 

Details of digestion experiments Nos. 451-462 42 

Digestion experiment No. 451 43 

Digestion ex peri men! No. 4."n > 43 

Digestion experiment No. 453 44 

Digestion experiment No. 454 4."s 

Digestion experiment No. 455 45 

Digestion experiment No. 456 4t> 

I tigestiori experiment No. 457 47 



6 

Experiments on the digestibility of bread — < fcmtinued. 

Details of digestion experiments Nos, 161—462 Continued. 

I tigestion experiment No. 458 17 

I digestion experimenl No. 4S9 

Digestion experiment No. 460 

Digestion experimenl No. 461 

I digestion experimenl No. 462 

Summary of result.- 51 

« reneral summary ">l 

Income and outgo of nitrogen 66 

Metabolic products in feces .".7 

Treatment of feces with pepsin 

Treatment of feces with ether, alcohol, hoi water, and bmewater 

Artificial digestion of bread with pepsin N 

Comparison of coefficients of digestibility of protein in bread as deter- 
mined by different methods 

Investigation of methods for separation of feces 

Lampblack as a marker H 

Action of pepsin apon treated gelatin capsules 88 

Knotted strings as marker- 7<» 

Summary of experiments w ith marker- 7") 

Method adopted for digestion experiments with men at the Maine ;. 



THE DIGESTIBILITY AND NUTRITIVE VALUE OF 
BREAD. 



INTRODUCTION. 

The grade of wheat flour most commonly used in making white 
bread is known as straight or standard patent. In the production of" 
this flour by the modern process of milling, the bran and aleurone 
layers and the germ are removed by preliminary treatment and the 
remainder of the kernel is then ground. The bran is left out because 
if included it would make the flour coarse, and the germ is removed 
because it contains the oil of the wheat, which is likely to become ran- 
cid and spoil the flour, and which acts upon the other constituents of 
the flour so that the bread in baking is darkened in color. 

Both the aleurone layer, or inner portion of the bran, and the germ 
arc rich in nitrogenous matter and mineral salt>. and the germ is also 
much richer in fats than the other portions of the wheat kernel: hence 
it is frequently claimed that the white flours are overrefined, that the 
valuable parts of the wheat are left in the waste products, and that 
the fine grades of patent flour consist of little else than starch. The 
coarser grades of flour on the market, the so-called Graham flours, are 
milled in accordance with the idea of avoiding the apparent waste 
occurring in the production of the finer flours. In milling Graham 
flour the whole of the wheat kernel is ground and no bolting or 
sorting process is employed, the resulting product being in reality 
wheat meal. 

It was found, however, that the presence of so large a proportion of 
the bran as there is in flour of this description seemed in many cases 
to result in an irritation of the delicate mucous lining of the intestine. 
As a compromise between the coarse Graham -and the fine white flours 
an intermediate product was placed upon the market, to which the 
name "wholewheat" or "entire wheat" was given. The manufac- 
turers of this flour claim that it is prepared by removing only the 
woody part of the bran, leaving the aleurone layer and the germ, and 
that it therefore contains all the nutritions part of the wheat kernel 
without the irritating bran. A- a matter of fact, the attempt- t<> 
remove onlv the bran do not seem in all cases to have been entirely 



successful, as the appearance of the Hour often -how- thai part of 
the coarse material still remains in the Sour. 

From the standpoint <»l' average chemical composition the floura i on- 
taining the whole <>i' the wheat kernel would appear to be more nutri- 
tious than those from which the bran and germ have been removed. 
A comparison of tin' figur< - for the composition of the different grades 
of flour, given in Table 1. shows somewhat large] proportions of pro- 
tein and fat in the coarser flours. Disregarding the fact that all grades 
of flour contain large proportions of starch, which is a valuable nutri- 
ent, the advocates of the coarse flours appear to assume that their 
nutritive value is directly proportional to the amount of nitrogenous 
matters which the\ contain, believing, apparently, that all the nil 
enous compounds of the wheat are of equal food value. But there 
are reasons for thinking that this may not be the case. It is certain 
that the various compounds in that part of the wheat kernel which 
predominates in the white tl<»ur> are not identical with those of the 
bran or the aleurone layer, and it is believed thej differ from them in 
nutritive value. 

The actual test of nutritive value, however, is not the quantity of 
nutritive ingredients contained in the Hours, hut the proportions that 
may l»e digested and absorbed from them, a- only material that can be 
digested can serve the body for nourishment. A considerable amount 
of investigation of the digestibility and nutritive value of different 
grades of wheat flour has been carried on in Europe, with very inter- 
esting and valuable results, hut few of these are applicable to the 
conditions common in tin- country, because the flours used were 

somewhat different from those w hieh are conn i here, and the breads 

were made hy methods not ordinarily followed by our bakers. Fur- 
thermore, the experiments have Keen conducted generall}' in such ways 
that it i- not possible to make strict comparison of the results so as 
to -how the relative nutritive values of the different grades of flour. 
In order to permit of reliable comparison the different Hour- should 
l>e -round from the same lot of wheat, because of variations in the 
composition of wheat- from different sources, whereas generally the 
European investigations of this charactei were made wit li flours pur- 
chased in tin' open market 

In connection with the nutrition investigations carried on under the 
auspices of the Office of Experiment Stations, during the past few 
years studies of tin- digestibility and nutritive value of bread made 
from di He re nt grades of flour ground from the same lots of wheat have 
been made at the Maine and Minnesota experiment stations for the 
purpose of accumulating data which will serve in answering ques- 
tions regarding the effects of different methods of milling upon the 
nutritive value of Hour. The experiments described in the following 



pages, which were conducted at the Maine Experiment Station during 
the years 1899-1902, were in continuation of those reported by the 
same authors in a previous bulletin" of this series. 

The investigations reported in the present bulletin comprise experi- 
ments with men on the digestibility of bread from different grades 
of flour, including determinations of the income and outgo of nitro- 
gen; artificial digestion tests with pepsin solution of all the breads 
used in the experiment- with men: estimation of the amounts of met- 
abolic nitrogen in the feces obtained in the experiments; and a study 
of methods of marking and separating feces in digestion experiments. 
The details of the work carried out along these lines are given in the 
sections that follow. 

EXPERIMENTS ON THE DIGESTIBILITY OF BREAD. 

Thirty-two digestion experiments with men were completed. They 
were divided into three series, in each of which three men served as 
subjects. Three kinds of flour — Graham, entire wheat, and standard 
patent — were used in both the first and the second series, all three 
grades in each series being ground from the same lot of wheat: though 
the lot used in the second series was different from that in the first. 
In the third series still another lot of wheat was used. In this case, 
however, the experiments with Graham flour were not completed, 
because the flour did not appear to be true to name, as explained later. 

The first series, comprising experiments Nos. 431-441, was similar 
to those previously reported:" that is, the diet contained a relatively 
large amount of bread eaten with few other materials, which were 
of such a nature that their digestibility could be assumed for the 
conditions of the experiment, and the digestibility of the bread alone 
could therefore be calculated. The last two of the 11 experiments 
in this series differed from the others in that the diet was much 
smaller, having been designated " half ration." the purpose being to 
compare the digestibility of rations of different size. Experiments 
Nos. 431— 133 were similar tests with three subjects in which bread 
from white flour formed the main part of the diet: Nos. 434-436 
were like the former, except that entire-wheat bread was used; and 
Nos. 437-439 weresimilar, but with Graham bread. Experiment- Nos. 
440 and 441 were like Nos. 431-433. but the ration was reduced to 
one-half the usual amount. 

in the second series, comprising experiments Nos. 44i J -4."»< | . and 
the third series, Nos. 4.M-4»'>l\ the ration was a simple mixed diet in 
which the number of food materials other than bread was larger, and 
the amount of bread, though huge, was smaller in proportion to the 

" l'. S. Dept. Agr., Office of Experiment Stations BuL s ~>. 



10 

total ration than was the case in experiments Nob. 431 Hi. The pur- 
pose in the later experiments was to determine the effect of the dif- 
IVivnt kinds of bread upon the digestibility <>t' an ordinary mixed diet 
as a whole rather than to estimate the digestibility of the bread alone. 
Of the experiments in the second series, Nos. 442 ill were three with 
a mixed diet, in which about a half of the total protein was furnished 
by white bread; Nos. 445-447 were similar but with entire-wheat 
bread, and Nos. 448 4.".". three others of the same kind, with Graham 
bread in place of the white bread. In the third series, Nos. 451 
were similar to Nos. -Hi'— H4 of the second series, l>ut with entire-wheat 
bread, and Nos. 454-456 were similar experiments with white bread; 
likewise Nos. 457—459 were with entire-wheat bread and Nos. !••" l''>"_' 
with white bread. 

DESCRIPTION OF FLOURS. 

The flours used in these experiments, which were furnished by Prof. 
Harry Snyder, of the Minnesota Experiment Station, were ground 
from the same lots of wheat, at the same time mid in the same mill 
as those used in digestion experiments made by him and reported in 
earlier bulletins" of this Office. The numbers of the flours in the 
following description of samples are the same a- those in the table of 
composition on page L4. 

Nos. 6133 and 6443 were straight or standard patent flours from 
the best quality of hard spring wheat grown in the Northwest, milled 
in the same way as the bread Hour most commonly found in the mar- 
ket. This grade of flour consists of the first and second patent* and 
the first clear grade. About 72 pounds of straight patent flour is 
obtained from 1"<> pounds of screened and cleaned wheat such a- was 
used in these experiments. These two samples were from different 
lots of wheat. The former was used in experiments No-. j:;i 133 and 

the latter in Nos. 442 444. 

Nos. 6142 and t;444 were so-called entire-wheat or natural flours, 
which are obtained by removing a portion of the bran and grinding 
the remainder of the wheat kernel. They are of a coarser texture 
than the patent grades. About 85 pound- of entire-wheat flour i> 
milled from LOO pounds of cleaned wheat. These two samples were 
from the -a i ne \<>\- of wheat :i- No-. 6133 and 6443, respectively. No, 
6142 was used in experiment- No-. l-".l 136 and No. 6444 in Nos. 
440-447. 

No-. 6155 and 0442 were Graham flours, or wheat meal-, produced 
by grinding the whole of the wheat kernel, bran and all. The pres- 
ence of the bran prevents fine pulverization; and since in the manu- 
facture of tine ( irahani flours no sieves or boltingcloths are einplo\ ed. 
the Hour contains many coarse particles. No. 6155 was from the same 



i - I -• !•• \.i . I 'it,. • i Experiment Stations Bui* lul ami L26. 



11 

lot of wheat as Nos. 6133 and 611:2, and No. 6112 was from the same 
lot as Nos. 6443 and 6441. These two samples of Graham flour were 
used in experiments Nos. 437—439 and 448-450, respectively. 

No. 6597 was a white flour, not strictly a straight grade, but more 
properly called a blend. It consisted largely of straight grade, but 
with a little of the lower grades and the germ included. This sample 
was used in experiments Nos. 451-456 and Nos. 450-462. 

No. 6598 was an entire-wheat flour from the same lot of wheat as 
No. 6597. It was used in experiments Nos. 451-153 and Nos. 157-159. 

PREPARATION OF THE FOOD. 

All the breads consumed in the experiments here reported were spe- 
cially prepared from the flours described above. For the first series 
of experiments. Nos. 131-411, the breads were made with yeast and 
the ingredients were not weighed. In the later work baking powder 
was used, and all the constituents were weighed in order to secure 
greater uniformity of composition. In the second series, experiments 
Nos. 442-450. the bread was made according to the following formula: 
Flour. 15o grams; salt. 8 grams; sugar, 30 grams; baking powder, 12 
grams, and whole milk, 375 grams. To this enough water was added 
to give the dough the right consistency. The baking was done in an 
Aladdin oven over a solid-flame gas burner. The temperature was 
carefully regulated and the resulting breads were of very uniform 
character. The breads used in the third series, experiments Nos. 151- 
162. were made in the same way except that water was used instead of 
the whole milk. 

The meat used in all but three of the second and all of the third 
series of experiments was prepared from shoulder clod of beef, slightly 
corned. The bone. fat. and connective tissues were removed from the 
cooked meat as completely as possible and the meat ground in a meat 
cutter. After thorough mixing, the meat was placed in glass fruit 
jars, enough in each to serve for a single meal, the covers loosely 
adjusted, and the jars immersed nearly to the shoulder in a large kettle 
of water, which was gradually heated to the boiling point. After the 
heating had been continued for thirty minutes, the covers were firmly 
screwed down and the jars removed, cooled, and stored in a refrigerator. 
I hough tlii—. last was probably a needless precaution. To insure ster- 
ilization, on two succeeding days the covers were loosened and the jar- 
again heated tor thirty minutes at LOO < '. Enough meat was thus 
prepared to last through an experiment, <»r in one case through two 
experiments of four days each. When a jar was opened, the entire 
contents were removed and thoroughly mixed, since the juice- separated 
more or less from the meat during the sterilizing process. The portion 
for each subject was weighed in a porcelain dish and warmed. 



L2 

One of the well-known brands of canned boned chicken was also 
fofmd to be admirably adapted to the purpose <>t' the experiments. 
The contents of several cans were passed through a meal cutter and 
thoroughly mixed. Thus prepared the material was placed in glass 
fruit jars, about 250 grama to the jar, and sterilized in the manner 
described above. The amount in one jar was sufficient for :i rapper 
for three — iit»i*-«-i — _ 75 grams being allowed for each man, leavings 
margin for samples. The chicken was compressed into cakes in ■ 
mold constructed for the purpose and served cold. 

A sufficient amount of potatoes for a day's use was boiled on the day 
preceding cadi experimental day. These were prepared in different 
way- as required, some being sliced and fried for breakfast and the real 
mashed, seasoned, and warmed for dinner. 

In experiments Nos. 431-441 only the crumb of the bread was 
eaten. Bread was prepared for each meal l>\ cutting the loaf in thin, 
uniform slices, removing the crust from each, and placing the slices 
in four piles in rotation, one being reserved for each man and the fourth 
Bet aside and prepared for analysis as described below. In the later 
experiments (Nos. 442 462) the crust was not removed. A loaf u:i> 
selected for each man and exactly one-fourth by weight removed for 
analysis. The reserved portion was thinly sliced and dried at a tem 
perature of a Wont 50 C. After three or four days the samples were 
removed from the drying ovens, allowed to stand for several days 
exposed to the open air of the laboratory, and then finely ground in a 
hand mill. 

When beef or chicken was served, 25 grams weresel aside for anal- 
ysis and dried at .'»() ( '. Sample- of LOO grams each were taken from 
the potatoes morning and night. In each case the -mall -ample- of 
beef, chicken, or potatoes were combined into a composite sample, 
thus necessitating but one analysis of each kind of food for an experi- 
ment of three day-. 

SEPARATION OF FECES. 

Bach experiment of the first series, No-, i.'.l ill. began \\ ith a sap- 
per of milk with which wa- taken a gelatin capsule tilled with lamp- 
black. During the two day- following, the experimental diet (which 
consisted largely of the bread studied) was eaten, and the experiment 
then terminated with a breakfast similar to the preparatory supper, 
consisting of milk with a capsule of lampblack. Each experimental 
period, therefore, included eight meal- an initial and closing meal, 
yielding feces of an unusual and marked character, and two full days 
of three meal- each, constituting the experiment proper, yielding feces 
of the usual character. In the examination of the feces those portions 
were rejected which were strongly colored with Lampblack. That por- 
tion appearing between these two ** markers n was assumed to be derived 



13 

from the food studied, and was collected, dried, weighed, sampled, and 
analyzed. The accuracy of the digestion experiments, as is always the 
ease, was largely dependent upon the exactness with which the sepa- 
ration of the feces could be accomplished; no refinements of methods 
of analysis can atone for failure to achieve this. It is believed that in 
the work here reported the separations were tolerably exact, although 
in a few instances the line of demarcation was less sharp than was 
desirable. This matter is discussed at some length on pages 68-77. 

In the second and third series, experiments Nos. -±4:2-±62, the pre- 
liminary supper and supplementary breakfast of milk were omitted. 
The lampblack used for marking the feces was inclosed in gelatin cap- 
sules coated with shellac,* one of which was taken at breakfast on the 
first day of the experiment and another with the breakfast next follow- 
ing the last day of the experiment proper. In this case, therefore, the 
feces of the experiment included all that excreted from the time the 
lampblack first appeared until the appearance of the second lampblack. 

COLLECTION OF TJRINE. 

The urine was collected during each of the experiments, beginning 
with the time of the first meal and ending at the same time on the day 
following the last one of the experiment. As previously noted," these 
periods were not chosen in the belief that the nitrogen of urine thus 
collected represented the protein katabolism of the food studied, but 
because in the absence of any means of marking the urine, and the 
lack of definite information concerning nitrogen lag, i. e., the time 
between the ingestion of nitrogen in the food and its excretion in the 
urine, the periods of the experiment were the most convenient for the 
purpose. The total amount of nitrogen eliminated in the urine was 
determined, and also the heat of combustion of the organic matter. 
In experiments Xos. 431-141. which covered two days each, the deter- 
minations were made in the urine for the whole period of an experi- 
ment rather than in that for separate days; but in experiments Xos. 
412-ltii! the urine for each day was weighed and analyzed by itself. 

ANALYSES OF FOODS AND EXCRETORY PRODUCTS. 

Analyses, including determinations of heats of combustion, were made 
of Hours, breads, and all other food materials used in the experiments 
excepi sugar, lard, and apples, and also of all excretory products, the 
met hods of analysis followed being for the most part those recom- 
mended by the Association of Official Agricultural Chemists. fl The 
determinations of the ether extract in the \\^-i'> were unsatisfactory, 
duplicate determinations failing to give sufficiently concordant results. 



«U. S. Dept. A-r.. Office of Experiment stations Bui. 85, p. 11. 
'' r. S. Dept. A.gr., Division of Chemistry Bui. 46, revised edition. 



14 

The heats of combustion of food, feces, and urine were determined 
bv burning samples of dried material in the bomb calorimeter* in the 
usual manner. The milk ami urine were prepared l'<>r combustion 
according l<» K diner's method, as follows: A weighed absorption block 
of cellulose, * previously dried for two days <>\<t sulphuric acid, was 
placed in a platinum capsule and saturated with a known amount <>f 
milk or urine. The capsule and Mock were then dried at a tempera 
ture not exceeding 70 C, after which the absorption block was again 
saturated with a known amount <>t' substance and dried. The Mock 
and material were then burned and the results obtained were cone. ted 
for the heat of combustion of the absorption block itself, this latter 
factor being the average of determinations for a considerable number 
of blocks. 

COMPOSITION <>l' POOD MATERIALS. 

The results of analyses of the flours and all f I materials used in 

these experiments are given in Table I. 

Table [.^-Composition of flours and foods used in digestion > vperinti 



mi:; 
6597 

6142 

til 1 1 
r,.v.is 
6155 
6442 
6131 

fiV.Yl 

6195 
6196 
6446 
6447 
6448 
( ;t;;,;, 

liii.V, 

6657 



6] 13 

(ill I 
61 15 
1,171 
6472 
6473 

6633 

6673 
6674 
6675 
6166 



Kiii'l of materia] 



Flour: 

straight grade from hard spring 

wheal 

Do 

Blended flour from soil winter 

\\ beat 

Entire wheal from same lol aa 6133. 
Entire wheal from same lol a* 6443 
Entire wheat from same lol 
Graham flour from Bame lol as 6133. 
Graham flour from sa i 

White l. read from flour No. 6133 

do 

do 

do 

w hite bread from Hour No. 6443 

....do 

do 

w hite bread from Hour No. 6597 

.....do 

do 

do 

do 

do 

Entire-wheat bread from Hour No 61 12 

...do. • 

do 

En tire- w heat bread from flour No. 6444. 

...do 

do 

Bntire-v heat bread from flour ' 

....do 

....do 

do 



do 

Graham bread from Hour No. 61 



13.35 
10.99 
10. i:: 
12.94 
10.51 
10.61 

B.10 

87.90 

38. 79 
1J. 16 
12. 58 
11.8] 
12.70 

12.64 
11.77 
18. II 
13.06 

88. 1 1 
38 u7 
11.65 

lu.su 
ll.su 

I • 01 



Protein< 



12. 

1 I. 19 

10.56 
13.00 
14.88 
11.81 
14.00 
15.63 
9.21 
8.10 

- 

'.'.71 

ii. 59 
6.64 

6 54 

8.04 
7.67 
7.76 

7. |u 

7. 27 

7.(Ni 

7. I-. 
7. '.'7 





Carbo- 




fat. 


hy- 
drates. 


\«h. 


Perct. 






1. 13 




O.fiO 


1. 10 




.49 


l.ll 


71. Hi 


- 




72.61 


1 . 22 


1 , 85 


71.95 












70.97 


2.00 


2.09 


69.9] 




1 . 79 


-i 72 




2. 17 






1.56 


19 19 




I 65 


19.67 




I .1 






1.57 


18. 28 


1.90 


1.61 


18.20 




. ii, 




1 71 


iu 


18. ,7 


1 -1 






1 " 






1 79 




is. 17 


1.71 












1.27 




11 10 














1.78 


i 84 






1 Ml 








|S Ml 


1.81 
















17. Hi 






17 2 ■ 










2.4] 







I ■olllt.ll>- 



1 004 

2.711 

2. 1 1 • 

2 74* 
2 116 



".lour. Amer. Cbem. Boc , 26 1 1903 i 

6 Land w. Vers. Stat., 17 (1896), p. 297. 

c Current usage la here followed In the factor 6.25, which assumes 16 per cent of nitrogen In protein 
iu the different products. It would, of course, be more corrcet to adapt the factor to the actual com- 
position which is variable. Bee Atwater and Bryant, Connecticut Storre) Station ftpt , 1899, p. 76. 



15 

Table 1. — Composition of flours and foods used in digestion experiments Nos. 4S1—462- 

Continned. 



Sample 
number. 



Kind of material. 



Protein 



Carbo- 
hy- Ash. 

drates. 



Heat of 
combus- 
tion 
per gram. 



04". 1 
0475 
6497 
64535 
6676 
6452 
6476 
6498 
6636 
6677 
6450 



01 3^ 
014s 
6159 



0134 
0140 
6147 
015s 
6197 
6449 
6474 



'iraham bread from flour No. 6155. 
Graham bread from flour No. 6442. 

....do 

....do.. 39. 

Beef, corned 54. 

...-do - 72. 

....do 70. 

... .do 71. 

....do 71. 

Chicken, canned 

....do 

...do 

....do 

....do 

Potatoes, boiled 

....do.. 



Peaches, canned' 

....do 

Milk, whole 

....do 

.-..do 

:...d0 

.—do 

....do 

....do 

Butter 

.-..do... 



....do... 

....do... 
....do... 
....do... 
....do... 
....do... 
....do.'.. 
....do.fr. 
Apples' - . 
Sngarc .. 
Lard e ... 



Per et. 

■ " 
10.25 
10. 33 
10.08 
25. 44 
21.16 
22. 14 
22.30 
22. 26 
27.66 
27.16 
27. 56 
27.78 

3.41 
2.55 
2 : 
.56 
.31 

3^44 

3! 31 

3.56 

3. *1 

i!i9 
.44 
.44 

.50 

.44 
1.13 
.94 



1.12 
.40 



PercL 

2. 56 
2.14 
2. 16 

2.09 

16.59 

3. >1 

4.66 

1.19 

1.79 

13. 62 

12.53 

12.55 

12.76 

12.08 

.11 

.04 

.06 



4.70 
5.00 

5. 80 
4.40 
I 28 

4.30 
4.30 
79.25 
s-5. 13 
80. 21 
•so. 4? 
77. 23 
-v 4 

84.46 

- 

so. 45 
.50 



100. 00 



PercL 

42. 97 
45.83 
46.06 
45. 75 



38.14 
21.-5 
20. 27 
14.59 
14.00 
4.07 

4. 26 
4.27 

"• 
5.04 
5.52 

5. 07 



.41 
1. 62 
.66 
.90 
.90 
14.20 
100.00 



pfrct. 
1.41 
2.49 
2.60 
2.52 
3. 07 
2.22 
2.92 
4.53 
4.14 
2.00 

1.96 
2.22 
2.06 
1.44 
.98 
.97 
.30 
.41 



.68 
.69 

.69 
3.55 
1.84 

,■.::- 
2.05 
3.10 
2.76 
1.91 
1.66 
2.11 
2.11 



Calories. 

2.514 
2.712 
2. 735 



1.537 
1.654 

1. 390 

2. 715 

. a 

2. 703 
2.692 
2. 685 
1. 7m7 
1.014 
.959 



.812 

.712 

.811 

. 020 

«7.436 

a 7. 917 

«7.1~A 

a 7. 951 

•17.207 

7. 596 

7.340 



■- 



3.959 
9.300 



"Energy computed by use of factors, 5.5 calories per gram for protein and 9.3 calories for fat. 

& Composition in part assumed from other analyses. 
'•Composition assumed. 



COMPOSITION" ()F FECE8. 



The composition of the feces collected in the experiments with dif- 
ferent kinds of bread is shown in Table 2, the results being calculated to 
a water-free basis, since the amount of water in the fresh feres ha- no 
bearing upon the calculation < >f the results of the digestif m experiments. 



lfi 



-jr.. gtibstnna of fere* from tl'ujrrtiim expn 



Sample 

IIIIIIltilT. 



Wlni obtained. 



Nitr..- 
i." ii. 



Protein 












19.89 




15.61 




14.80 


85.17 














11.74 


19. 16 


10.75 


21.51 


11.62 




19.80 




15.51 


1438 


14.70 






14.15 


17.61 


IJ. in 




12.84 


9.81 


10.87 


12.84 




7 77 


:'.:'. "7 


10.19 




B.91 




16.59 


51.61 










16.53 




11.85 




15.22 


16, 11 




52. 1 5 


10.52 


18. 18 




18. 1" 






12. 12 


18.74 











combo* 

tin ii |h r 

gnm. 



6137 

6149 
6150 
6151 
6160 
-■li.l 
6162 
6199 
6200 
6 156 
6457 
6458 
6478 
6 179 
6480 
6500 
6501 
6502 
6640 
6641 

- 
6659 
6660 

6681 

.;r,vj 



Experiment 
Experiment 
Experiment 
Experiment 
Experiment 
Experiment 
Experiment 
Experiment 
Experiment 
Kxi.i_Tiin.-nt 
Experiment 
Experiment 
Experiment 
Experiment 
Experiment 
Experiment 
Experiment 
Experiment 
Experiment 
Experiment 
Experiment 
Experiment 
Experiment 
Experiment 
Experiment 
Experiment 
Experiment 
Experiment 
Experiment 
Experiment 
Experiment 
Experiment 



No. 131. 
N... 132. 
No. 133. 
No. 134. 
No. 435. 
No. 136. 
No. 137. 
No. 138. 

No. 440. 
No. 441. 

No. II-'. 
No. 443. 
No. 444. 
No. II"'. 
No. 446. 
No. 117. 
No. 148. 

No. 4 IV. 

No. 150. 
No. 151. 
N... 152. 
N... J.»:l. 



No. 154. 
No. 455. 
No. 456. 
No. 157. 
No. 158. 
No. 159. 
No. W0. 
No. 461. 
N... !••.-'. 



I I. 
L19 

3 n 

7.1H 
7.98 
7.06 

6. 54 
5.02 

1.03 

7. 19 
8.24 

7.71 

- 
■ 

7.71 
7.7U 

• • 



in i.i 
36 II 

I 

29. 17 
20. 19 

12.60 



ll.ll 

17 II 

16, 18 

11. 17 
II. 1» 

17 75 

II 7.. 

14.94 

10.64 
11.64 

11.09 

12.01 
12.17 



5 172 



STATISTICS « IF I KIN i.. 

The following table shows the amount, nitrogen content, and heat of 
combustion of the urine as collected in the different experiments: 

Table '■'<. — Nitrogen content and heat of combustion of nrini in digestion 
Nos. 431-46S. 





Subject 


**■ '""i"""- 3SSL 


Nitrogen 


iii urine. 


imbuattoo 
of urine. 


number. 




r. r 




6139 

61 in 
r.l II 
6152 


P.H.M ... 

J.C.T 

W. Ii. w ... 
P.H.M ... 
.1 c T 


Experiment No. 131 

Experiment No. 132 

Experiment No. 133 

Experiment No. 134 


1. 163 
2,610 

lull. 


1.-.7 19.43 

1.78 

1 hi 

18. in 
I 71 24.10 

17.99 


164 

.146 

111 




6154 


W.B.W... 

P 11 M 


Experiment No. 136 






.1 C T 




161.1 










P. II. M ... 
J.C.T 

E. R.M ... 














Experiment No. 142: 






1,209 

1. \:<- 
1. 105 


1. 02 

l 21 


ll.ji 069 
11 17 

.069 










llll 




















.I.K.K ... 


Total for I da 
Experiment No. 148: 
















8ft 












6460 


1,102 

■ 


1.57 13.62 .1ft 

■ 
-- 
1 II 10.93 .lir.' 


ln7 








109 






Third day 


















Total for Ida] 






8,606 




49. HK 




867 






== 





17 

Table 3. — Nitrogen content and heat of combustion of urint in di<je.<tion experiments 
Nos. 431-46 /—Continued. 



Sample 
number. 



6461 
6464 



64*1 
6484 
6487 



64 vj 

64vS 

-• 

6491 



64*3 
64*6 
64>y 
6492 



6503 
6506 
6509 
6512 



6504 
6507 
6510 
6513 



6505 

650- 
6511 
6-514 



6643 

6646 
6649 

6652 



6644 

66 1 ! 

■ 



Subject. 



Whence obtained. 



Experiment >o. 444: 
First day 

Second day 

Third day 

Fourth day 



Total for 4 days. 



Experiment No. 445: 

Fir^t day 

Second day 

Third day 

Fourth day 



Total for 4 days. 



Experiment No. 446: 

First day 

Second day 

Third day' 

Fourth day 



Total for 4 days 

Experiment No. 447: 

First day 

Second day 

Third day" 

Fourth dav 



Total for 4 days. 

Experiment No. 44-: 

First day 

Second dav 

Third day' 

Fourth day 



Total for 4 days . 

Experiment No. 449: 

First day 

Second dav 

Third day". 

Fourth dav 



Total for 4 da vs. 



Experiment No. 450: 

First day 

I day 

Third day". 

Fourth day 



Total for 4 day. 



Experiment No. 451: 

First day 

Second dav 

Third day 

Fourth day 



Total for Idays. 

Experiment No. 152: 

First day 

S» nd dav 

Third day 

Fourth dav 



Weight 
of urine. 



Gram.;. 

1.211 

970 

1,034 



Nitrogen in urine. H«« of combustion 



P S^- Amount. 



Per cent. 
0.93 
1.39 
1.59 
1.55 



1. 270 

■ a 

1.043 
1,072 



4.674 



Grant*. 
11.26 
13. 49 
16.44 
11.33 



Calories. (Maries. 

103 

. 107 104 

. 116 120 



,099 


1.20 


_■_ 


1.43 


,218 


1.01 


,238 


1.37 



13. 19 

is. 33 
12.30 
16.% 



60. 



1.18 
1.41 
1.52 
1.85 



9.11 
17. 33 
17.95 
15. 35 



1.48 



17.56 

17.41 



1.18 

1.61 



.94 
1.41 
1.94 

I 



11.94 
18.17 

- _ 
17. 15 



. 19 



. :> 



. 073 

.072 

- - 



. -_ 



.10S 

. "-2 



. 100 . 

I 7 

: 



915 
1,079 


L87 


13. 54 
20. 18 


.113 
.114 


104 

123 


4.310 . 




62.74 .. 




> ~ 









1,638 
1,165 


1.12 
1.10 


18. a 
12. -2 




79 










426 













998 

1. 043 


1. 43 

1.50 


: - 27 
15. 65 


.091 
.093 


91 


3.214 .. 




47.14 .. 




313 



1.230 


1.09 


13.4 


.091 


112 


1 . 707 


1.10 


■ ■ 


- 


14:'. 


1 . 222 


1.19 


14.5 


ffi 


104 


22 


1.04 


9.6 


- 





















1,076 

1.371 


- 


- 
11.7 
12. 5 


J 

■ 
- 


Ill 



Total for 4 days 



51675— No. 143—04- 



18 



Tablb 3. Nitrogen content and heat of combustion of urn* 
No*. 431 ';>•;■■ Continued. 






Sample 
aumber. 


Subject 


Whence obtained. 


of iiritn- 


ii urine. 


Mll.ll-tlc.II 

of urine 


Propor 

tlotl. 


Amount. 


Pet 






E.E.N.... 


Experiment No 


Gramt. 

17J 

1,390 


Per '•'»'. 


19.7 
18 B 


K'l 


1 .1 


lit, IS 








0651 


















E.F.B.... 


Total for idaya 

Experiment No. 154: 






5,304 




59.0 




537 










6661 


1,838 
1,260 
I, 186 


69 
L08 

in 


12.7 
18. i 
18.1 
7.0 


Ul 


[22 
















H" 


6670 










E. K..M ... 


Total for (days 

Experimenl No. 156: 






5,014 








420 












1,269 
1,377 

1. 148 




10 9 


ll.i 


-- 


6665 


























E. E.N.... 


Total for B 'lays 

Experimenl No. 166: 














4,094 




33.4 




337 












1,638 
1,690 

1 . S92 
2,179 


.90 
,78 
.00 


11 7 
12. I 

11 I 


076 
.122 












6669 








6672 










E. F.B.... 


Total for I days 

Experiment No. 167: 






7. 299 




57.0 














6683 


1. 17n 

1 . 257 
1,306 


. 96 
1.04 
1.08 

.90 


11.0 

18 1 

ill 


.115 
,118 


,44 


6686 






11. 








11* 


6692 










E. EL If ... 


Total for 1 'lays 

Experiment No. 158: 






4,801 




48.1 




530 












1,205 

1. 162 

1,273 


.71 

•• 


10. 1 

9. 1 
10.0 
11.2 


.117 
084 

lirj 
lo-.. 


i n 


iwist 








6690 








6693 










E. K. N . . . . 


Total for l 'lays 

Experiment No. 169: 






5,296 

J. IT'." 
l. 150 
1,602 

• 




40.7 




541 




. .1 
LOO 








11 * 


.081 

117 


17', 










0691 






176 






Fourth day.... 


117 




K. I". B . ... 


Total for 1 .lays 

i tperimenl No. 100: 










|„ u 




591 












1,827 

1. 107 

1. UNI 


LOO 

90 

LOO 


11 • 
12.7 
14.0 


Ill 

120 




6704 






100 


6707 


















E. ELM ... 


Total for I dayi 
i sper hi No. nil : 






1 711 




49.2 




.V2»i 










6702 


1,064 

1 . 161 


:: 


- - 
in 6 
in i 


.099 

111 




6706 






101 


i.Tii- 








1,711 






lin 




E. i:. N . . . . 








5,228 








490 




Experimenl No. UB 










1,580 
1,644 


- 

7o 

- 

1 09 


17 .. 
in B 
11 8 


... 








1 daj 


1 4 










6712 












Total for i da 






6, 178 




52. 1 




642 











iriin- for tin- da 



19 

DETAILS OF DIGESTION EXPERIMENTS NOS. 431-441. 

The experiments of this series, Nos. 431-441, in which the purpose 
was to determine the digestibility of the different kinds of bread 
alone, covered short periods, namely, two days each. The white 
bread was made from flour No. 6133, the entire-wheat bread from 
No. 0142, and the Graham bread from No. 6155, described on pages 
10 and 11, all of which were ground from the same lot of hard spring 
wheat. The diet was very simple, consisting of the bread studied and 
enough milk, butter, and sugar to enable the subject to eat it with 
relish. Some coffee was taken as a beverage, but as this contained a 
negligible amount of nutrients, it is not included in the tables. The 
crust of the bread was rejected, only the crumb being used. Each 
man was allowed, within certain limits, to eat as much as he pleased. 

The subjects were students from 19 to 23 je&vs of age. The 
3'oungest and heaviest of these was of somewhat more active habits 
than the others and had a more vigorous appetite. Toward the close 
of the experiments he went into training for athletic field contests, 
which markedly increased the amount of food eaten. 

As noted elsewhere/ it seems to be the case that the various articles 
of food which comprise a mixed diet are more digestible than the same 
articles when eaten alone. For this reason, as well as to increase the 
palatability of the diet over that of a ration of bread alone, it was 
thought best to allow the use of the other foods mentioned with the 
bread experimented on. In order to calculate the digestibility of the 
bread alone from the results obtained with a diet of such a nature, 
it was necessary to assume values for the digestibility of the accessory 
foods. The factors used in the experiments previously reported were: 
For fats of milk and butter. 99 per cent; for protein of milk and 
butter, 98 per cent; for milk sugar, 98 per cent, and for cane sugar. 
99 per cent. These figures are more or less arbitrary, but they were 
based on the best information available. With the exception that the 
factor 98 per cent was used for both milk and cane sugar, the same 
figures were employed in the following tables in computing the "esti- 
mated feces from food other than bread.'' 

The manner in which these factors are applied may be illustrated by 
figures from experiment No. 431. From Table 4 it will be seen that 
of the total 227.3 grams of protein consumed in the two days, 79.6 
grains was supplied by the milk and butter. If it be assumed that 98 
per cent of the protein of milk and butter was digested, the undi- 
gested portion, namely, -i per rent of 79.6 grams, or L.6 grams, should 
appear in the feces. The total amount of protein in the feces was 9.4 
grams. Deducting from this the undigested protein of the milk and 
butter, T.n grams of the protein of the feces tnusl be credited t<> the 

<*U. s. Dept. Alt., Office of Experiment Stations BuL 85, i>. 15. 



20 

bread ingested. The total amount of digestible protein was 217.9 
grams; dividing this by the total protein eaten, i'l'T.-". grams, gives 
95.9 per cent as the coefficient <>f digestibility of the total protein in 
the diet. The protein in the bread eaten was 117.7 grams, of which 
7.8 grams appeared undigested in the feces, leaving L39.9 grama of 
digestible protein from the bread alone; which divided by the total 
protein contained in the bread eaten, 147.7 grams, gives 94.7 per cent 
as the estimated coefficient of digestibility of theprotein of the bread 
alone. 

By the use of the other factors given, the digestibility of the tat and 
carbohydrates are similarly computed. 

The method of calculating the proportion of energy actually avail 
able to the body may Likewise be illustrated by applying it in experi 
merit No. 431. Here the digestible protein from the whole diet. 217.9 
grams, multiplied by L.25, the average number of calories which it i- 
assumed would escape in the organic matter of the urine for every 
gram of protein digested from the food, gives 272 calories as the 
amount of energy lost in the urine through incomplete (.Nidation. If 
this amount l>e deducted from the total energy of the digested food, 
8,233 calories, the difference, 7,961 calories, represents the energy of 
the total food actually oxidized in the body. The proportion of the 
energy of the total food that would be actually available to the bodj . 
!C> per cent, is the quotient obtained by dividing the energy of food 
oxidized, 7,961 calories, by the total energy of the food eaten. 8,379 
calories. 

By a similar process the energy from the bread alone that was 
actually utilized by the body may likewise he computed, only in this 
case it is first necessary to estimate the energy of the digestible nutri- 
ents of the bread. For this purpose t he energy of the feces from f 1 

other than bread was computed by use of factors < for protein 5.65, for 
fat 9.4, and for carbohydrates 1.15 calories per gram), and this was 
subtracted from the energy of the total feces as determined, the 
remainder being taken as the energy of t be est imated feces from I. rend. 
The difference between this and the total energj of the bread is the 
energy of the digestible nutrients of the bread. In the case of exper 
iment No. i:;i this was l.">71 calorie-. The energy lost in the urine 
corresponding to the digestible protein of the bread was 1 139.9 L.25 i 
175 calories, which subtracted from the energy of the digestible nutri 
cut- of the bread gives t,396 calories as the total amount of energj 
from bread actually oxidized in the body. Dividing this by the total 
in the bread consumed, t,667 calories, gives the proportion of the 
energy of the I' read actually available to the body, 94.2 per ••cut. 

Although the energy of the urine wa> determined, in the calculation 
of the availability of the energj of the total food and of the bread 
alone it was assumed, principally for the sake of uniformity with exper- 



21 

iments previously reported, that 1.25 calories of energy would appear 
in the urine for every gram of digestible protein in the total food or 
in the bread alone. The relation of the values determined to the factor 
is discussed elsewhere (p. 52). 

The details of the experiments follow: 

DIGESTION EXPERIMENT NO. 431. 

Kind of food . — White bread, with milk, butter, and sugar. 
Subject.- P. H. M. 

~\Yeig1tt. — At beginning, 182.2 pounds: at close. 17^ pounds. 
Duration. — Two days, with six meals. 



Table 4. — Results of digestion experiment No. 431. 



Sample 
number. 




Weight 
of ma- 
terial. 


Total 
organic 
matter. 


Protein 
(Xx6.25). 


Fat. 


Carbo- 

hy- 
drates. 


Ash. 


Energy. 


6131 




Grams. 

782. 
934.8 
2U9.6 
2, 125. 
95.2 


Grams. 
482. 7 
523. 8 
168.6 

276.3 
95.2 


Grams. 

72.0 
75.7 
2.5 
77.1 


Grams. 

14.0 
23.1 

166.1 

99. 9 


Grams. 
396.7 
425. 

"'99.'3' 
95.2 


tin i ins. 
7.3 
8.0 
7.4 
17.4 


Calories. 

2, 212 


6132 
6134 
6135 


do 

Butter 

Milk 

Sugar 

Total 


2, 455 

1,558 

1.774 

380 













1,546.6 


227.3 


303. 1 


1,016.2 


40.1 


8,379 




25. 6 21 . 


9.4 
1.6 


5.1 


6.5 
3.9 


4.6 






Estimated feces from food 




8.2 


50 




Estimated feces from 










12.8 


7.8 


2.4 


,0 




96 




Total amoun t d igested . 
Estimated digestible nutri- 










1. ">:!•"'. G 
993.7 


217.9 
139.9 


298. 
34.7 


1,009.7 
819.1 


35. 5 


s.233 




Coeffieients of digestibility 








Per et. 


Per ct. 

98.7 


Per et. 
95. 9 
94.7 


Pi r et. 
98. :: 

93. 5 


Per ct. 
99.4 


Pi r rt. 
88.5 


Pi r rt. 

(98.3) 
(97.9) 

95. 




Estimated coefficients of di- 






Proportion of energy actu- 
ally available to body: 
















94.2 










1 







During this experiment the subject eliminated 2,192 grams of urine 
containing 1.60 per cent, or 35.1 grams, nitrogen. This makes the 
average nitrogen balance per day as follows: Income in food, 18.2 
grams; outgo in urine and feces, 18.3 grams; making a loss of 0.1 
gram nitrogen, corresponding to 0.6 gram protein. 



!>■_> 



DIGEST [OH i:\I'I:i:imi:m NO. 432. 

Kind of food. -White bread, with milk, batter, and sugar. 
Subject.- J. C. T. 

Weight {without clothing/).— Ai beginning, L21.6 pounds; at end, 
121.4 pounds. 

Duration. -Two days, with six meals. 

Tablb •">. — Remits of digestion • vperimeni \ 



Sample 
number. 




Weight 

nf 1IUI- 

terial. 


Total 
organic 

llliltlcr. 


Protein 


I'm. 


Carbo- 
hy- 
drate* 


A-!.. 




6131 




Grams. 
617.6 
646. I 

JIT. n 
1,075.0 


drum*. 

319.6 
862.2 

139.7 
93. 8 


Grams. 

17.7 
52. 1 


< in mi.-. 

16.0 


'.Vi.'j' 




1. H.l 


6132 


do 




6186 


Milk 






Total 











1,113.9 


142.0 


271.6 


700.3 








34.6 


•.27.7 
6. 'J 


- 


5.4 


12.7 

•j. a 








Estimated feces from food 






Estimated feces from 










21.5 


- - 


2.9 


9.8 




MB 




Total amount digested. 
Estimated digestible mitri 
ents in bread 

Coefficients of digestibility 










1,086.2 

660.2 


132. 4 
91.8 


200.2 
22.4 


087.6 


21.1 






Per el. 


J'erct. 
97 ■ 


Prr a. 
93.2 
91.2 


Per d. 

•- 




Prr ri. 

-,. 1 


Prrii. 

■ 

94, 1 




Estimated coefficients of di- 






Proportion of energy actu- 
ally available to body: ■ 









































During this experiment the subject eliminated L,163 grama of urine 
containing 1 . * "» T per cent, or !'.».4 grams, nitrogen. This makes the 

average nitrogen balance per day a< follows: Income in I" 1. 11.8 

grams; outgo in urine and feces, 10.4 grams; making a gain of 0.9 
gram nitrogen, corresponding (<> 5.6 grams protein. 



23 



DIGESTION EXPERIMENT NO. 431 



Kind of food. — White bread, with milk, butter, and sugar. 
Subject.'— W. B. W. 

Weight (without clothing). — At beginning, lit. 7 pounds: at close, 
142.6 pounds. 

Duration. — Two days, with six meals. 

Table 6. — Results of digestion experiment No. 433. 



Weight Total p^^ 
or ma- organic ,£ ™£™ 

Terial. matter. " N '~° 



Sample 
number' 



Carbo- 
| hy- 
drate-. 



Ash. 



Energy. 



6131 
6131 
6134 
61:35 



Grams. 

White bread 521.4 

do 

Butter 191.2 

Milk 1, 175.0 

Sugar 39. 8 



Total. 



Feces 22. 1 

Estimated feces from food 
other than bread 



Grams. 


Grams. 


Grams. 


321. 9 


48.0 


9.4 


339.5 


49.1 


15.0 


153. 8 


2.3 


151. 5 


191. 8 


53.8 


69.3 


39.8 













Gram---. 
264.5 
275.4 



Grams. 
4.8 
5.2 
6.8 
12.1 



Calories. 

1.475 
1,591 
1 , 422 
1, 232 

159 



.0 245.2 | 648.6 



5. -79 



17.5 



5.5 
1.1 



3.2 



128 
35 



Estimated feces from 
bread 



Total amount digested 1,029.3 

Estimated digestible nutri- 
ents in bread 649. 4 } 



242.0 
23.4 



Per ct. Pt r ct. 



Coefficients of digestibility 

of total food 

Estimated eoeiticientsof di- 
gestibility of bread alone. 
Proportion "of energy actu- 
ally available to body: 

In total food 

In bread alone 



Per ct. 

96.4 
95.5 



Per ct. 
9S.7 
95.9 



5, 751 
2,973 



Per ct. 
98.6 
98.8 



Perct. 
84.1 



Perct. 
(97.8) 
(97.0) 

94. 7 



During this experiment the subject eliminated 1,305 grams of urine 
containing 2. 06 per cent, or 26. 9 grams, nitrogen. This makes the aver- 
age nitrogen balance per day as follows: Income in food, 12.2 grams: 
outgo in urine and feces, 13-9 grams: making a loss of 1.7 grains nitro- 
gen, corresponding to 10.5 grams protein. 



DIGESTION EXPERIMENT HO. 134. 

Kimd of food. Entire-wheat bread, with milk, butter, and sugar. 
Subject.- P. II. M. 

Weight {without clothing). At beginning, L80.3 pounds; al close, 
1 7'.'..") pounds. 
Duration. Two days, with six meals. 



Table /. — Results of digestion • tperimeni 2Vi 



Sample 
number. 




Weigh! 

ul' ma- 
terial. 


Total 
Organic 

matter. 


Protein 




d rates. 


Ash. 








Qrame. 
662.6 
662. •-' 
692.0 

95. 6 

1, -150.0 

102.6 


Orams. 

303.5 
330.0 

84.7 
77.1 
184.2 
L02.6 


16. 2 
19. i 

. i 

. i 

i'.'. ■.. 


14.6 
16.8 


102 '. 


7.1 

1 - 
U.6 






.do . ... 






....do 




61 16 






61 1; 


.1.. 


7 in 


61 18 


Milk 












Total 












1,409.9 


199 '• 


276.5 
















i.] 19 


7*. 9 


(17.8 
6.6 


27.8 

Id 


li:5 


28.6 


11.1 






Estimated Feces from f I 


10 




Estimated feces from 










G1.2 


26.H 


'.i. 'J 


25. 2 








Totalamountdigeated. 
Estimated digestible nutri- 










1,402.1 

9C0.1 


171.2 
121.6 


205.0 




31.2 












Coemcients of digestibility 
of total food 








J '( >■ ct. 


Ft r ct. 
95. i 
94.0 


J'erct. 
BJ.9 


lYrct. 


Per ct. 
:>:. 1 
97.C 


1'crcl. 


JYrci. 




Estimated coefficients of di- 








Proportion of energy actu- 
ally available to body: 









































During tin- experimenl ilt«' subject eliminated 2,610 grams of urine 
containing 1.06 per cent, or 27.7 grams, nitrogen. This makes the 
average balance per day a- follows: Income in t'<><>'l. L6 grams; outgo 
in urine and feces, l»'».l grams; makings l»>-- of ".1 gram nitrogen, 
corresponding t<> 0.6 gram protein. 



25 



DIGESTION EXPERIMENT NO. 435. 

Kind of food. — Entire-wheat bread, with milk. 
Subject.— 3. C. T. 

Weight {without clothing). — At beginning, 119.9 
121.1 pounds. 
Duration. — Two days, with six meals. 



butter, and sugar, 
pounds; at close, 



Tabt.e 8. — Rixults (if digestion e.rp, riment No. 4S-'. 



Sample 
number. 




Weight Total 
of ma- organic 
terial. matter. 


Protein 
X 6.25). 


Carbo- 
Fat. hy- 
drate-. 


Ash. 


Energy. 






Grams. 

394.0 
413. 6 
506.0 
208.2 

92.0 
S75. 

99.0 


'Tram*. 
212.6 
209.3 
283.5 
178.2 
74.2 
111.1 
99.0 


Grant/. 
31.7 
31.3 

'.9 

.4 

30.1 


Grams. 

10.2 
8.0 
11.5 
177. 3 
73.8 
43.7 


Gram.-: 
170. 7 
170.0 

23::. 7 

""37.Y 
99.0 


Grams. 

5.0 
4.1 
4.7 
3.8 
s.6 
6.9 


Calories. 

1,002 


6144 
6145 
6146 
6147 
6148 


do 

do 

Butter 

do 

Milk 

Sugar 

Total 


964 

1,313 

1,654 

689 

740 














1,167.9 


133.7 


324.5 


709.7 


33.1 






PeeeS 

Estimated feces from food 






6150 


85. 5 


70.9 
6.2 


22.4 

.0 


14.3 34.2 
2.9 2.7 


14.6 


488 




Estimated feces from 
bread 

Total amount digested. 
Estimated digestible nutri- 








64.7 


21.8 


11.4 31.-5 




445 






1,097.0 
640.7 


111.3 
80.5 


310.2 
18.3 


675. 5 

541.9 


18.5 


6,269 
2 834 




Coefficients of digestibility 








Per ct. 


Per ct. 
93.9 

90. S 


Per ct. 
78.7 


Per it. 
95.6 
61.6 


Pt r ct. 
95.2 
94. 5 


Pt r ct. 


Pt r ft. 
(92.8) 

90.7 




Estimated coefficients of di- 
gestibility of bread alone . 

Proportion" of energy actu- 
ally available to body: 




















B3.4 

















During- this experiment the subject eliminated 1,035 grams of urine 
containing 1.80 per cent, or 18.0 grams, nitrogen. This makes the 
average nitrogen balance per day as follows: Income in food. 1<>.7 
gram-: outgo in urine and feces. 11.1 grams; making a loss of 0.4 

gram nitrogen, corresponding to 2.5 grams protein. 



26 

DIGESTION EXPERIMENT \<>. 136. 

Kind of food. Entire-wheat bread, with milk, butter, and sugar. 
Subject. ' W. B. \Y. 

Weight {vrithmd clothing). At beginning, Itl.l pounds; at dose, 
14:1.1 pounds. 

Duration. Two days, six meals. 

Table '.». Results of digestion • tperimeni A 



Sample 
number. 




Weigh) 
ol ma- 
terial. 


Total 
organic 
matter. 


Protein 




hy- 
drates. 


Ash. 




6143 
6144 
6145 
6146 

CUT 
61 1* 




'.in in*. 

161. 1 
11". u 
100.0 

'..;. i 
850.0 


Grams. 
164.9 

246.6 

■ 

78.6 

HiT. ;i 

18.8 


Orams. 

■_•:;. l 
34.9 

. 1 

. 1 

29 J 


LO.0 

78. 1 
12, 6 


124.8 

l-'.t.7 
202. 1 


ii 
l B 


■ 


...,1«> 




...do 


1,148 


Butter 

do 

Milk 


718 




pi, 


















955.7 


122. 2 


232. 1 


001.4 


29.9 












53.1 


45.7 

1. 1 


17.4 
.6 


7.8 
2.1 


1.7 


7.4 






Estimated i.e.- from i 1 






Estimated feces from 










41.8 


16 * 












Total amountdiges ted. 
Estimated digestible nutri 










910.0 


104. 8 
75.4 


224.3 
20.7 


6H0.9 
497.fi 












Coefficients of digestibilitj 










95. 2 


81.8 


Prr rl. 
78, 1 


Per ct. 


Per et. 


7Vrrt. 




Estimated coefficients of di- 
gestibility "i" bread alone. 
Proportion "i energy actu- 
. ally available i" bodj : 












::::::::: 

































During this experiment the Bubjecl eliminated 1,326 grams of urine 
containing L.78 per cent, or 23.6 grams, nitrogen. This makes the 
average nitrogen balance per day as follow-: Income in food 
grains; outgo in urine and feces, 13.2 grams; making a losn of ''>.\ 
grams nitrogen, corresponding to 21.2 grams protein. 



27 

DIGESTION EXPERIMENT NO. 4: ; m . 

Kind of food. — Graham bread, with milk, butter, and sugar. 
Subject.- P. H. M. 

Weight {without clothing). — At beginning, 178.5 pounds; at close, 
179.3 pounds. 

Duration. — Two davs, with six meals. 



Table 10. — Results of digestion experiment No. 437- 



Sample 
number. 


Weight Total 
of ma- ' organic 
terial. matter. 


Protein 


Fat. 


Carbo- 
hy- 
drates. 


Ash. 


Energy. 






Grams. Grams. 
956.2 510.8 
977. 2 523. 8 
197.4 169.8 

2,125.0 | 291.2 
103.0 | 103.0 


Grams. 
76.2 
78.9 
1.0 
77.2 


Grams. 
23.0 
25.0 
168.8 
123.2 


Grams. 

411. 6 
419.9 

"'90*8' 
103.0 


Grams. 
14.9 
13.8 
4.0 
17.2 


Calories. 

2. 457 
1.575 


6157 
61.=* 


do 

Butter 


6159 


Milk 


2, 010 
411 




Total 



Estimated feres from rood 













233. 3 


340.0 


1,025.3 


49.9 


8.829 


6160 


139.4 


121.9 


31.1 
1.6 


16.3 
2.9 


74.5 
3.9 


.." 


699 

51 




Estimated feces from 













29.5 


13.4 


70.6 




648 




Total amount digested . 
Estimated digestible nutri- 












1. 476. 7 
921.1 


202. 2 
125.6 


323. 7 
34.6 


9.50. 8 
760.9 


32.4 


s,130 
4. 185 




Coefficients of digestibility 








Per rt. 


Per d. 

92.4 


P> r rt. 
86. 7 
81.0 


Per d. 

1 

72.1 


Pt r rt. 

- - 

91.5 


Per O. 

64.9 


Pf r rt. 
(92.1) 
(86.6) 

- a 




Estimated coefficients of di- 
gestibility of bread alone. 

Proportion of energy actu- 
ally available to body: 


















83.4 















During- this experiment the subject eliminated 2,960 grams urine 
containing- 1.04 per cent, or 30.8 grams, nitrogen. This makes the 
average nitrogen balance per day as follows: Income in food. 1S.»> 
grams: outgo in urine and feces. 17.9 grams: making a gain of 0.7 
gram nitrogen, corresponding to 4.7 grams protein. 



DIGE81 h >N EXPERIMENT N< '. 438. 

Kind of food.- Graham bread, with milk, butter, and sugar. 
Subject.- J. C. T. 

Weight (without clothing). At beginning, L19.6 pounds; at close, 
L20.5 pounds. 
Duration. — Two days, with six meals. 

Tw.iK II. — Results of digestion experiment No. . 



Sample 
number. 




Weight 
of ma- 
terial. 


Total 
organic 

matter. 


Protein 


Pat, 




7.1 








Grama. 

507. 1 
306.6 

90. ii 


Grams. 
361.1 
271.9 

119.9 

90.6 


1 :■ 


(Irani*. 

18.0 
262. 1 

50 : 


218.0 
90.6 




8157 
6158 
6159 


do ...... 

Butter 

Milk 

Sugar 

Total 
















1,107.1 


128. 1 


342.1 


686. '.< 


31.1 














96.7 


81.1 

6. 1 


IS. 5 

. 7 


10.4 
3.1 


52.2 
■J. 6 


15.6 






Estimated feces from food 






Estimated f a from 










71.7 


17.8 


7.3 


49.6 








Total amount digested. 
Estimated digestible mitri- 












1,026.0 
558.3 


109. 6 
77.0 


331.7 




15.5 


6.099 




Coefficients of digestibility 








Per d. 


Per n. 

92. 7 


Per ct. 
81.2 


Ptr rl. 
97.0 

7'.. 1 


91.8 


Prrrt. 


Prrrt. 




Estimated coefficients of di- 








ProportiOD of energy actu- 
ally available to body: 









































During this experiment the subject eliminated L,046 -ram- of urine 
containing 1.73 per cent, or I s . 1 grams, nitrogen. This makes the 
average nitrogen balance per day as Follows: Income in food, I".*-' 
grams; outgo in urine and feces, 10.5 grams; making ;i loss of 0.3 
gram nitrogen, corresponding to L.9 -rain- protein. 



29 



DIGESTION EXPERIMENT NO. 139. 

Kind <>f food. — Graham bread, with milk, butter, 
Subject.— W,. B. W. 

Weight (without clothing). — At beginning, 113.2 
141.7 pounds. 

Duration. — Two days, with six meals. 



and sugar. 

pounds; at close. 



Table 12. — ]{< suits <>/ illr/rstimi experiment No. 439. 



Sample 
number. 


Weight 
of ma- 
terial. 


Total 
organic 
matter. 


Protein 

<X '•,.25.. 


Fa I. 


( larbo- 

hy- 
drates. 


Ash. 


Energy. 


6156 
6157 
6158 
6159 


Graham bread 

do 

Butter 

Milk 

Sugar 

Total 

Feces 

Estimated feees from l 1 


Grams. 
689. 1 
603. 1 

206. 2 
S50. ii 
60. 2 


Grams. 

368.3 
323. 1 
177.3 
116.5 
60. 2 


Grams. 

54.9 
18.7 
1.0 
30.9 


Grains. 
16. 6 

15.1 
176.3 
49.3 


Grams. 
296.8 

25;.. :; 

'"36.3" 
60.2 


Grams. 

10.8 

1.2 
6.9 


1.71:: 

1.517 

1,645 

801 

240 
















1,045.7 


135.5 


257. 6 


652. 6 


30.4 


5,919 


6162 


91.9 


79.4 
1.8 


19.7 
.6 


10.7 
2.3 


49. 


12.5 


466 




Estimated feces from 
bread 

Total amount digested . 
Estimated digestible nutri- 








T^T. 


74.6 


19.1 


8.4 


47.1 




434 




966.3 

617. 1 


115.8 
84.5 


246.9 
23.6 


603.6 
509.0 


17.9 


5. 453 




Coefficients of digestibility 








Pt r Ct. 


Per et. 
92.4 


Per ct. 
85. 5 
SI. 6 


Per ct. 
95.8 
73.7 


Per ct. 
92. 5 
91.5 


Per Ct. 
58.9 


Per ct. 

TJ2.1 ) 




Estimated coefficients of di- 
gestibility of bread alone. 

Proportion of energy arm- 
ally available to body: 























v.. >; 





















During- this experiment the subject eliminated 1,385 grams of urine 
containing 1.7-1 per cent, or 21.1 grams, nitrogen. This makes the 
average nitrogen balance per day as follows: Income in food. 10.8 
grams; outgo in urine and feces. 13.6 grams; making ;i loss of 2.8 
grams nitrogen, corresponding to 17.5 grams protein. 



30 



l.\ I'l.lMMKN I 



140 



Kind of food. White bread, with milk, batter, and sugar (half 
ration). 

Subject.— P. II. M. 

Weight {without clothing). At beginning, L75.fi pounds; ;it close, 
171.7 pounds. 

Table L3.— ifewtfts of digestion experimeni No. . 



Sampl 
numbe 



6195 
6196 

ill 'JT 
6198 





Weight 
of ma- 
terial. 


Total 
«.rjr;uii« 
matter. 


Protein 

24 9 
17.8 


1.7 
L6 


11- 

I7.ii 






White bread 

....do 


Qratiu. 
301.0 
281.0 

116.5 

17.0 


177.6 
167. 1 
89. 7 
67. 1 

I7.il 


1.0 


819 


Milk 

Sugar 








Total 








122. 1 














Feci - 


29.5 


37.0 


11.4 

. 1 


1.1 


18.4 
1.6 


9.2 


■ H »» 


Estimated feces from food 










Estimated feces from 




31.0 


11.0 


6.1 


















511.8 
811.0 


55.3 
37.4 


114.9 


341.6 
270. 1 


3.0 




Estimated digestible butri- 








Coefficients of digestibility 


Perct. 


Per ct. 

'.HI. 'J 


Per ct. 
77.8 


Perct. 
94,1 

::i. 1 


94. 1 


Per d. 




IMiinnted coctticit'iilsdl' di- 




Proportion of energy act*] 
ally available t<> Bod} : 






































During this experiment the Bubjecl eliminated 1,889 grams of urine 
containing L22 per cent, or 23.0 grams, nitrogen. This makes the 
average nitrogen balance per day as follows: Income in food, 
grams; outgo in urine and feces, L2.5 grams; makings lossof I grams 
nitrogen, corresponding to 24.7 grams protein. 



31 



DIGESTION EXPERIMENT NO. Ml. 

Kind of food. — White bread, with milk, butter, and sugar (half 
ration). 

Subject.— J. G. T. 

Weight (without clothing). — At beginning, 116.1 pounds: at close, 
115.6 pounds. 

Duration. — Two days, with six meals. 

Table 14. — Results of digestion experiment No. 441- 



Sample 

number. 


Weight 
of ma- 
terial. 


Total 
organic 
matter. 


Protein 
(NX6.25). 


Fat. 


Carbo- 
hy- 
drates. 


Ash. 


Energy. 






Grams. 

406.0 
444.4 
104.8 
1.062.5 
47.6 


Grams. 

239. 6 
264.8 
81.4 
132. 8 


Grams. 

3,7. 2 

.5 
35.2 


Grams. 
6.3 
7.3 
80.9 

46.8 


Grams. 

199.8 
220.3 

'"5u.~8~ 
47.6 


Gram*. 
2.7 
4.2 
3.2 
8.0 


Calories. 

1,105 

1,205 

755 

863 

190 


6196 
6197 
6198 


do 

Butter 

Milk 
















766. 2 


106.4 


141.3 


518.5 


18.1 






Feces 

Estimated feces from food 






6199 


46.2 


24.4 


11.2 


5.8 
1.3 


7.4 
,0 


5.1 


172 




Estimated feces from 












20.4 


10.5 


4.5 


5.4 








Totalamount digested. 
Estimated digestible nutri- 
ents in bread 

Coefficients of digestibility 










741. 8 
484.0 


95.2 
60.2 


13-5. 5 
9.1 


511.1 

411.7 


13. 


3, 946 
2.162 




Per ct. 


Per ct. 

96.8 
95.9 


Per ct. 
89.5 
85. 2 


Per ct. 
95.9 
66.9 


Per ct. 

VS.* 
9S.7 


Per ct. 
71.8 


Per et. 
(95.8) 
(93.6) 

92.9 




Estimated coefficients of di- 






Proportion of energy actu- 
ally available to body: 
















90.4 















During this experiment the subject eliminated 1,046 grams of urine 
containing 1. 72 per cent, or 18 grams, nitrogen. This makes the average 
nitrogen balance per day as follows: Income in food, 5.3 grams: outgo 
in urine and feces, 9.9 grams: making a loss of 1.6 grams nitrogen, 
corresponding to 28.5 grams protein. 

SUMMARY OF RESULTS. 

The results given in detail in the foregoing pages are summarized in 
Tables 15 and L6. The first of these gives the digestibility of the 
nutrients and availability of the energy of the total food: the second, 
the calculated digestibility of the nutrients and availability of the energy 
of the bread alone. 



32 



Table !■">. — Sumi 



tri) of ili'l' slum i 



. /„ rim* nts -Digestibility of nutrii utsnnd availability of 
■ ,,, ray of Mai food. 



Kx- 


Subject. 


Kind of food. 


1 


efficients ofdlgestibilitj 




\\Hila- 
WUtyof 


im-nt 
iium- 
ber. 


Total 
organic 
matter. 


Pro 

I. in. 




by 


Aah. 


121 


l'.H.M ... 
J.C.T 

W.B. \\ ... 

IMI.M ... 

1 iT.... 
W.B.W... 

P. II. M . .. 
.1 C.T ... 


White bread, milk, butter, and 


97. 5 








Ml 












.do.... 












98. 1 


96.2 


98.8 


98.7 


82.7 


94.6 




Entire-wheat bread,milk, butter, 




r.i 


95. i 
95. 2 


86.0 




97 1 


71. 1 






do 






..do 












94.8 


85.0 


%.o 


96.3 


68.5 


91 . 6 




Graham bread, milk, butter, and 
sugar 




137 


92. 1 
92, 1 


• 


97.0 


91.8 
92. 5 


„., 




139 


W.B.W .. 

P. II.. M ... 
J.C.T .... 


do 

Average of 3 above 

White bread, milk, butter, and 
Bugar | half ration i 








B5. 9 


96. o 


92.3 


57.9 


89.7 


140 

111 






91 1 


■ 


71.- 






95.0 


86.2 


95.0 


96.7 


18.2 











Table L6. — Summary of digestion experiments — Digestibility of nutrients and antih 

of i in i-'/i/ of bread alotu . 



Ex- 
peri- 
ment 
num- 
ber. 


Subject. 


Kind of food, 


Coefficients •■!' digestibility. 


bilityol 


Total 
organic 

mailer. 


Pro- 
tein. 




Carbo- 

i.y- 


i:;i 


l'.H.M ... 
J.C.T . . 






91.2 






•.M a 




.... do 




133 


W. B. W- . 


do. 






r.n.M ... 

J.C.T .... 










•.'7. 9 


93.8 












i:;i 




XI. 9 

7-. 7 


97.0 
61.6 

7- 1 96. I 






do 




(36 


W. l;.w ... 


do ... 






l'.H.M ... 
J.C.T ... 








- 


80. 8 












187 


-- 


81.0 






- 


do 






W.B.W_. 

IMI.M ... 
J.C.T 


do 






88.8 


81.3 










140 


90.2 


85.2 


66.9 98.7 
94, l 




111 


do 






„: 


81.8 

















[t is noticeable that in the experiments with small rations, Nos. 140 and 
441, which were like Nos. \-'<\ and 132 in every respecl excepl thai the 
quantity of food was reduced <>im- balf, i In • digestibility was consider- 
ably lower than in those with full ration-. The Largest difference was in 
the case of the protein. These results are the opposite of those obtained 



33 

by Snyder a in similar tests. He found that in general the digestibility 
of the smaller ration was somewhat higher than that of the larger 
ration of similar food, though the differences were slight. 

The results of the experiments here summarized agree in the main 
with those of the earlier experiments made at this station and those 
made at the Minnesota Station in this respect, that the nutrients of 
the white breads were more completely digested than those of the 
breads from either the entire-wheat or the Graham flour. In the pres- 
ent experiments, however, the average digestibility of the Graham 
bread was higher than that of the entire-wheat, whereas in the other 
experiments it was lower. The significance of the results obtained 
will be best illustrated by applying them to the flours used in these 
experiments. 

The advocates of the coarser flours attach great importance to the 
fact that these materials contain more total protein than the ordinary 
white flour. As previously pointed out, the only fair comparison is 
that between the three grades of flour as milled from the same lot of 
wheat. From the analyses given in Table 1 it will be seen that for the 
fresh flours used in this series of experiments the percentage of pro- 
tein in the entire wheat (So. 6142) was but a trifle higher than that in 
the white flour (No. 6133), though the difference between these and 
the Graham flour (No. 6155) was larger. The relations between the 
protein of the three flours were much the same in the water-free 
material also, as shown by the following figures : 

Table 17. — Percentage of protein in different kinds of flour. 





Kind of flour. 


Protein. 




In fresh 
flour. 


In water- 
free flour. 




Per cent. 
12. 75 
13.00 
14.00 


Per cent. 
14. 40 





















The digestibility of the protein of the bread made from these flours 
was found in these experiments to average, for standard patent. 93.8 
percent; for entire wheat, 80.S per cent; and for Graham, 81.3 per 
cent, Multiplying the percentage of total protein in each grade of 
flour by the coefficient of digestibility here given shows that the 
three flours in the fresh state contained the following amounts of 
digestible protein: Standard patent flour, L1.96 per cent: entire-wheat 
flour, 10.50 per cent; and Graham flour, 11.38 per cent. Thus it 
appears that the subjects actually obtained more protein from the 
white flour, which had the lowest proportion of total protein, than 
from the Graham flour, which had the highest. 

«U. S. Dept. kgr., Office of Experimenl stations Bui. 101. 
21t>7.->— No. 143—04 3 



34 

From such facta as these it is plain that caution should be observed 
La drawing deductions from analytical data. The results of analyses 
must be correctly interpreted if tin* deductions regarding nutritive 
value drawn from thorn are to be «»t' any real worth. 

DETAILS OF DIGESTION EXPERIMENTS NOS. 442-450. 

The experiments of this series were carried <>ut in the spring of L901, 
with breads made from standard patent, entire-wheat, and Graham 
flours, all ground from the same lot of hard spring wheat. This l<>t 
of wheat, however, was different from that used in the previous 
experiments. While the object in the present series was in general 
the same as in the experiments preceding, a comparison of the diges- 
tibility of breads made from different grades of Hour ground from the 
same lot of wheat, the problem was now limited to a determination of 
the relative rather than the absolute digestibility of the breads under 
investigation. More specifically, the present experiments were 
intended to show 7 the relative effects of the three kinds of bread upon 
the digestibility of a ration more like the ordinary diet than that which 
was used in the previous experiments. At the same time it was neces- 
sary to make up a ration in which the ratio of bread to the other food 
should remain constant and the kinds and amounts <>t' food other than 
bread should be always the same. In order that an\ deduction might 
be drawn concerning the effect of the different kinds of bread upon 
the digestibility of the total diet, it was necessary that tin 1 proportion 
of bread be fairly large. The actual amounts of the food materials 
used were fixed upon by a series of preliminary tests in which the men 
followed the dictates of their appetites. The individual requirements 
were found to be so nearly alike that uniform rations could be used 
for all. While the bread constituted a smaller part of the ration in 
this series than in experiments Nos. 431-441, about one-half the total 
protein and energy was derived from it. The diet in the present 
series was much more varied, beef, chicken, potatoes, and canned 
peaches being added to the bread, butter, milk, and sugar used in the 
former tests. 

No attempt has been made to estimate the coefficient of digestibility 
of the bread alone. It ha- been assumed, in considering these experi- 
ments in their bearing on the subject of the nutritive value of different 
sorts of flour, that any variations due to differences in digestibility of 
the breads would appear in the values for the digestibility <>f the 
whole diet, as the only factor which varied in the different experiments 
was the character of the Hour used to make the bread. The white 
bread used in this series of experiments was made from the Hour rep- 
resented by sample No. *;44:>. the entire-wheat bread from Hour No. 
6444, and the Graham bread from Hour No. 6442, described on page 10 
of this bulletin. 



35 

The following bill of fare for a single day will serve as an illustra- 
tion of the size and variety of the ration adopted. The menu for each 
experimental day was made as nearly like this as possible, the amounts 
of each food material being kept the same each day, with the excep- 
tion of the bread, the variations in diet thus depending upon the com- 
position rather than quantity of the food eaten. The weights of bread 
consumed necessarily varied somewhat, since it is impossible to pre- 
pare two loaves of equal weight from the same materials, owing to 
fluctuations in water content. It may be assumed, however, that the 
three-fourths loaf eaten represented in each case practically the same 
weight of flour and other solids used in making the bread. 

-Menu for one day. 

Breakfast, 7.15 a. m. : j Dinner, 12.15 p. in.: 

Bread, three-quarters of a loaf, 559 Bread and butter, as at breakfast. 

grams for the day. Beef, 120 grams. 

Butter, 50 grams for the day. Potatoes, mashed, 150 grams. 

Potatoes, 120 grams, sliced and fried, j Milk used in preparing potatoes, 50 

Beef, 50 grams. grams. 



Sugar, 50 grams for the day, 

Coffee, one cup. 

Milk for coffee, 25 grams. 



Supper 5.30 p. m. : 

Bread and butter, as at breakfast. 
Canned chicken, 75 grams. 
Canned peaches, 130 grams. 



While each man consumed daily his allotted portion of bread, he 
was not restricted as to the proportions which should be eaten at each 
meal. Equal liberty was allowed as regarded the butter. On a few 
occasions a subject expressed his readiness to add to the menu, but 
complaints that the amounts supplied were too great were rare. It is 
very doubtful if any improvement could have been made in these 
rations for the men under experiment, so far as quantity was concerned. 

The subjects of the experiments were three young men. J. E. F., 
26 years old, and W. H. E., 20 years old, were university students. 
E. R. M., 23 years old. was an assistant chemist at the experiment 
station, who had served as subject in preceding experiments and who 
by his constant presence and attention to details contributed much to 
the success of the work. 

The following tables, giving the results of the experiments in the 
the present series, are similar to those on previous pages in so far as 
they give the results for the total diet, but diner in that they do not 
show anything concerning the digestibility of the bread alone. 

DIGESTION EXPERIMENT NO. -±42. 

Kind of food. — Mixed diet, including white bread. 
Subject.— E. K. M. 

Weight (without clothing). — At beginning, L31.4pounds; at end. 131 
pounds. 

Duration. — Four days. April 15-18, 1901. 



S6 



Tabu L8.- Remits of digestion experiment A 



Sample 
number. 




Weight 
<>f ma- 
terial. 


Total 
organic 
matter. 


Protein 


Pat 


Carbo- 
hy- 
drates. 


Alb. 


Bnergy. 




White bread 


Qranu. Grams. 

i 137. 1 

160 198.8 

800 128. <J 

L.080 

200 179.2 

1,200 154.6 

83.0 


Oramt. 

117.0 
88.0 

2. 8 
42.7 


Oramt. Oramt. 
: IB7.fi 


Oramt. 


• 






10.9 

1.2 

176. l 

61. I 


117.8 

- 


6452 








1.844 


6449 








Milk 














10 
300 
160 


10.0 
US. 5 

•J 1.1 




KM. 








1.7 
.6 


22. 7 


.6 


llUI 






M 




Total 








2, 706. 


516.9 


898.6 


1,795.6 


99.4 


13.593 




Feces 

Amount digested 

Per cent digested 








6 156 


110.6 97.9 

2,608. 1 




49.0 
- K.T. •.' 
90.62 


16.3 


32.6 
1,768.0 

98. 1'.. 


12.7 


613 








Energy of food oxidized in 
















Per cent of energy utilized. 


::::::::::::::::: 














. 1 













During this experiment the subject eliminated 5,504 grams urine 
containing 56.7 grams nitrogen. This makes the average nitrogen 

balance per dayas follows: Income in food, 20.7 grams; outgo in urine. 
L4.2 grams, and in feces, 2 grams; making a gain of 4.5 gram- nitro- 
gen, corresponding to 28.1 grams protein. 

DIGESTION EXPERIMENT NO. 443. 



Kmdoffood. — Mixed diet, including white bread. 
Subject.-^. E. F. 

Weight (vrithout clothing). -At beginning, L40 pound-: at end. I pj.l 
pounds. 

Duration. — Four days. April L5-18, L901. 

Table L9.— Results of digestion experiment A 



Sample 
number. 




Weight 
of ma- 
terial. 


Total 

organic 
matter. 


Protein 


I'm. 


Carbo 

hy- 
drates. 


Ash. 


Bnergy. 






Oramt. 

2, 120 

160 

:;iki 
1,080 
200 
1,200 
-:■• 
10 
BOO 
160 


Grams. 

i. in. i 



"i:..Y:V 
i 79.2 
164 <; 

lii.ii 

24 l 


Oramt. 

117.li 

J. H 
42. 7 


Grams. 


1 168. 1 


Oramt. 




6451 
6452 


Beef, rib piece 

chi. ken 




10.9 

1.2 117:; 
176.1 


1,844 










Milk 
















Lard 




1.-.0 


•.<:! 






1.7 
.6 




.9 


180 






. 8 22. 7 






Total 










519. 1 


894.7 1.796.5 


99.6 


13.618 












6 T'T 


86.8 




43.3 

1 


12.7 I 18.5 
1 778.0 


12.3 


482 






13,136 
























Energy oi food oxidised in 












1 




Per cent of energy utilized . 





























37 



During this experiment the subject eliminated 3.505 grams urine 
containing 19.9 grams nitrogen. This makes the average nitrogen 
balance per day as follows: Income in food, 20.8 grams; outgo in 
urine, 12.5 grams, and in feces, 1.7 grams: making a gain of 6.6 grams 
nitrogen, corresponding to 11.3 grams protein. 

DIGESTION EXPERTMENT NO. H4. 

Kind- of food. — Mixed diet, including white bread. 
Subject.— W. H. E. 

Weight (without clothing). — At beginning, 150.5 pounds; at end, 
150.5 pounds. 

Duration. — Four days. April 15-18, 1901. 

Table 20. — Remit* of digestion experiment No. 444- 



Sample 
number. 




Weight Total 
of ma- organic- 
terial. matter. 


Protein 


Carbo- 
Fat. hy- 
drates. 


Aah. 


Eneigy. 






Grams. Grams. 

2,405 1,430.0 

460 


Grams. 
232.1 
U7.0 
83.0 
36.8 
2.3 
42.7 


Grams. 
28. 7 
76.3 
40.9 

1.2 
176.1 
51.4 


Grams. 
1,159.2 

"417.3" 

.8 
60.5 
83.0 


Grams. 
42.1 
16.9 
6.0 
15.6 
5.5 
-._ 



Calories. 
6.477 
1,361 










300 
1,080 

200 
1,200 
S3 
10 
300 
160 


455. 3 
179.2 
154.6 
S3.0 
10.0 
45. 5 
24.1 






1,844 


6419 




6453 


Milk 


854 




Lard 




10.0 
.8 




6451 




1.7 
.6 


43. 8 
•22.7 


.9 
.5 


160 










Total 










516.2 


395.4 1.7>7.3 


95.7 













6458 


69.3 


485. 6 

94.07 


12. 2 14. 2 
383.2 1.773.1 
96.91 ; 99.21 


12.3 

S3. 4 

-- ;- 
























413 




Energy of food oxidized in 


12,603 































During this experiment the subject eliminated 3.916 grams urine 
containing 52.3 grams nitrogen. This makes the average nitrogen 
balance per day as follows: Income in food, 20.6 grams: outgo in urine. 
13.1 grams, and in feces, 1.2 grams: making a gain of 6.3 grams nitro- 
gen, corresponding to 39.1 grams protein. 

DIGESTION EXPERIMENT NO. 415. 

EwndqffoocL — Mixed diet, including entire-wheat bread. 
Suibjeet.— E. R. M. 

If,////// (toithout clothing). — At beginning. L32.9 pounds; at end. 
132.5 pounds. 
Duration. — Four days. April 23-26, L901. 



38 



Table 21. — Results of digestion experiment A 



Weight Total 
ofnuv organi. 
terial. matter 



Sample | 
number. 



6471 
6476 
6476 

6450 
6474 
6477 



Entire-wheat bread . 
Beef, shoulder clod . 

Chicken 

Potatoes 

Butter 

Milk 

Bogai 

Lard 

Peaches 

Apples 



Total. 



Grams, drams. 



Feces 

A mount digested 

Per cent digested 

Estimated energy of urine.. 

Energy of food oxidized in 

the body 

Per centof energy utilized. . 



300 

1,080 

200 

1,300 

- 

10 
300 
160 



165. S 

171.1 
177.2 
83.0 
10.0 

15. 5 

j i.i 



Grams. 

162. i 
8L6 

1.9 



Granu. 

vi. :: 
27. I 

1.2 
168.9 



10. 

- 



18.8 

511.9 

91.30 



10.9 

96. '.»1 



Carbo- 
hy- 
drates. 



22. 7 



Oram*. 




1,155.0 












117.:: 


15.6 






71.8 


9.0 







1,757.2 



16.7 
79. 2 



Energy. 



1,107 

I -si 
l.u.l 

160 



ij.7:« 






During this experiment the subject eliminated 4,837 grains urine 
containing 608 grams nitrogen. This makes theaverage nitrogen bal- 
ance per day as follows: [ncome in food. i'l'.4 grams; outgo in urine, 

15.2 grams, and in feces, l.'.t grams; making a gain of .">.-". grams 
nitrogen, corresponding to 33J grams protein. 

DIGESTION KXl'ERIMKNT No. 446. 

Kind of food. — Mixed diet, including entire-wheat bread. 
Subject.— J. F. F. 

Weight (without clothing). — At beginning. L42.5 pounds; at end. 
142.3 pounds. 

Duration. — Four days. April 22-25, L901. 

Table 22. — Results of digestion experiment No. ;;';. 



Sample 

number. 




Weigh! 
of ma- 
terial. 


Total 

irganie 
matter. 


Protein 


Carbo- 

Fat. hy- 
<1 rates. 


A-h. 


Fnergy. 


&472 




j. 1 1 1 
720 
300 

1,080 

2IKI 

1,800 

• 
10 

160 


Grams. 

l. in.:; 

"486."s' 

171.1 
177.2 
88. 
10.0 

•J l.l 


Grams. 

162. i 
81.5 

19. :■ 


Grams. Grams. 
11. 1 1,164.8 





1.2 
168.9 

71 s 


- 


< alortm. 


6476 

0470 
6450 
6474 
6477 


Beef, shoulder clod 

Chicken 

Potatoes 

Butter 

Milk 

Sugar 

Lord 


1,107 

1,844 

1. MB 








10. 


M 




1.7 
.6 




--.'. 7 




un 




Apples 

Total 










560.0 


846.2 1,806.2 


102.3 


13, 546 




Fee,- 








647'J 


130.2 




65.8 
604.2 
90. "I 


12. 8 42. 4 


19.2 


663 




















Energy of food oxidized in 







12,649 










.:..:: :::: 














1 







39 



During this experiment the subject eliminated £,012 grams urine 
containing 59.7 grams nitrogen. This makes the average nitrogen 
balance per day as follows: Income in food. 22.1 grams: outgo in 
urine. 15 grams, and in feces, 2.2 grams; making a gain of 5.2 grams 
nitrogen, corresponding to 32.5 grams protein. 

DIGESTION EXPERIMENT NO. 447. 

Kind of food. — Mixed diet, including entire-wheat bread. 
Subject.— V?. H. E. 

Weig ht (without clothing). — At beginning, 155.5 pounds; at end. 
151 pounds. 
Duration. — Four days. April 22-25, 1901. 

Table 23. — Results of digestion experiment No. 447. 



Sample 
number. 


Weight 
i of ma- 
terial. 


Total 

organic- 
matter. 


Protein 
N ■ 6.25 . 


Fat. 


Carbo- 
hy- 
drates. 


Ash. 


Energy. 






Grams. 

■2. 411 

720 

300 

1,080 

200 

1,300 

83 

10 

300 

160 


Grams. 
1,447.8 

"455.' 3* 
174.1 
177.2 
83.0 
10.0 
45.5 
24.1 


Grams. 
233.1 
152. 4 
81.5 
36.8 
1.9 
49.5 


Grams. 
43.4 
27.4 
37.6 
1.2 
168.9 
55.9 


Grams. 
1,171.3 

'"417.Y 
3.3 
71.8 
83.0 


Grams. 
45.3 
16.0 
6.8 
15.6 
3.8 
9.0 


Calories. 
6,625 


6475 

6476 


Beef, shoulder clod 

Chicken 


1,107 

797 

1,844 


647-4 
6477 


Butter 

Milk 

Sugar 

Lard 

Peaches 

Apples 

Total 


1,468 

1,054 

329 






10.0 

.'s~ 


93 


6454 


1.7 
.6 


43.8 
22.7 


.9 
.5 


160 
46 








557. 5 


345.2 1,813.2 


97.9 


13,523 


6480 


117.3 




48.0 

509.5 
91.38 


15. 38. 3 
330.2 1.774.9 
95. 77 97. 89 


16.0 
81.9 
82.64 


618 






12,905 














Estimated energy of urine. 
Energy of food oxidized in 






396 














12,509 




Percent of energy utilized. 












92.50 

















During this experiment the subject eliminated 1.31" grams urine 
containing 62.7 grams nitrogeu. This makes the average nitrogen 
balance per day as follows: Income in food. 22.3 grams: outgo in urine, 
15.7grams. and in feces. 1.9 grams: making a gain of 1.7 grams nitro- 
gen, corresponding to 29.1 grams protein. 

DIGESTION EXPERIMENT NO. US. 

Kind of food. — Mixed diet, including Graham bread. 
Subject.— E. R. M. 

Weight (without clothing). — At beginning. 131.8 pounds: at end. 
131.1 pounds. 

Duration.— April 29 to May 2. four days, L901. 



40 



Table 24.— Results of digestion experiment A 



Sample 

number. 




Weight 
of ma- 
terial. 


Total 

irganic 
matter. 


iTcit.in 


hy- 
drates. 


A-li. 








Qrams. 

2, 180 

720 

300 

1,080 

200 

1,200 

83 

10 

300 

160 


l. MS. 9 

"456.8 
177.6 
166.7 

10.0 

24. 1 


264.2 
159. 1 

- 
14.8 






1.2 ilT.:f 
174.6 
51.6 










1 191 






"11 








6496 






6499 


Milk 
















I^inl 




10.0 








1.7 




! 






Apples 














362.4 1,766.6 


117.3 












6500 


193.1 




60.6 


15.0 
847. 1 


90.8 
1,674.7 


26.7 


981 






























Energy of food oxidized In 














12,144 







































During this experiment the subject eliminated r>.4l7 grams mine 
containing 66.1 grams nitrogen. This makes the average nitrogen 

balance per day as follows: Income in f I. 23.3 grams; outgo in 

urine L6.5 grams, and in feces, 2.4 grams; making a gain of 1. 1 grams 
nitrogen, corresponding t<> ~2~iS> grams protein. 

DIGESTION EXPERIMENT NO. 449. 



Kind df food. — Mixed diet, including Graham bread. 
Subject.— J. E. F. 

Weight {without <-l<>th'>n<i). At beginning, L42.3 pounds; :it end, 
14»'. pounds. 

Duration. — Four days. April 29 to .May 2, L901. 

Table 25. — Results of digestion < >i<-n,u.> 



Sample 
number. 




Weight Total 
of ma- organic 

tcrial. matter. 


Protein 


Pat 


rarlx.- 
hy- 

• Ira Us. 


Ash. 




6494 




Qrams. 
J 177 1. 160.3 



800 

177.6 
1,200 

lo 10.0 

Kjp 24. 1 


169. i 
1.8 


L2 
174.6 


1.1 in.;. 


21.0 




6497 
6498 
i; ISO 
6496 

6499 


Beef, shoulder clod 

Chicken 

Potatoes 

Butter 

Milk 

Sugar 

Lard 


1,191 

Ml 

1,844 
751 






10.0 






6464 


1.7 










Apples 

Total 




'.»' 22.7 








583.2 


862.8 1,769.8 


119.9 


13,549 


6501 


226.3 


75.0 
». 11 


22.9 95.8 
1,674.0 


31.6 


1,162 




Percent digested 














Energy of food oxidized in 
Hi.- body 














Per 'int of energy utiliz^l . 



























41 



During this experiment the subject eliminated 3,214 grams urine 
containing 47.1 grams nitrogen. This makes the average nitrogen 
balance per day as follows: Income in food, 23.3 grams; outgo in urine, 
11.8 grams, and in feces, 3 grams; making a gain of 8.5 grams nitrogen, 
corresponding to 53.1 grams protein. 

DIGESTION EXPERIMENT NO. 450. 

Kind of food. — Mixed diet, including Graham bread. 
Subject.- W. H. E. 

Weight [without clothing). — At beginning, 156.8 pounds; at end, 
155.3 pounds. 
Duration.— Four days, April 29 to May 2, 1901. 

Table 26. — Results of digestion experiment No. 450. 



Sample 
number. 




Weight 
of ma- 
terial. 


Total 
organic 
matter. 


Protein 
(Nx6.25). 


Fat. 


Carbo- 
drates. 


Ash. 


Energy. 


6495 




Grams. 

2,489 

720 

300 

1,080 

200 

1,200 

83 

10 

300 

160 


Grams. 
1.441.6 

"455.Y 
177.6 
156.7 
83.0 
10.0 
45.5 
24.1 


Grams. 
250.9 

82^7 

l.S 
44.3 


Grams. 

52.0 

33.6 
37.6 
1.2 
174. 5 
51.6 


Grams. 
1, 138. 7 

"iii'.k' 

1.3 
60.8 
83.0 


Grams. 

2l!o 
5.9 

15.6 
3.3 
8.3 


Calories. 
6,703 






1,191 






81J 






1,844 






1,549 




Milk 


751 






329 








10.0 
'.8 


93 






1.7 
.6 


43.8 
22.7 


.9 

.5 


160 






46 














578. 2 


361.3 


1,767.6 


118.2 


13,477 












6502 


176.3 




44.4 
523.8 
90.59 


15.7 
345.6 
95.56 


89.8 

1,677.8 

94.86 


26.4 
91.8 
77.67 


829 






12,648 




















431 




En erg v of food oxidized in 














12,217 


















90.65 

















During this experiment the subject eliminated 4.674 grams urine 
containing 67.5 grams nitrogen. This makes the average nitrogen 
balance per day as follows: Income in food, 23.1 grams; outgo in urine, 
16.9 grams, and in feces, 1.8 grams; .making a gain of 4.4 grams 
nitrogen, corresponding to 27.5 grams protein. 

SUMMARY OF RESULTS. 

The following table summarizes the results of experiments Kos. 
442-450: 



42 

Table 27. — Summary of digt Btion • xpt rinu nt» Not. ' u ttibUity of wutrit nit and 

em rgy of total food. 



Kx- 


Subject 


Kiml of bod. 


Coefficient* of digestibility. 


availa- 
bility ..f 
energy. 


IIHMlt 

num- 
ber. 


Protein. 


Km. 


Carbo- 
hydrates. 




(42 


E.R.M ... 
J.E.F .... 
W.II.K... 

E.R.M ... 

.1 E F 


White lin-inl unil mixed dlel . . . 
do 


/•- /• cent. 
90.5 
'.'1.7 
94.1 


/'. r i' ill 


/•« r <•' at. 


W 7 






....<!(. . . 






Average of 3 experiments . 

Bntire-wheal bread, mixed diet. 

. .do 






92.1 


96.5 


98.8 


87.3 


93.3 


445 


91.3 
90.0 

'.il. 1 


96.9 


97.8 


83.5 


92.9 




W.II.K... 

E. R. M . . . 
J.E.F 


do 






Average of 3 experiments . 

Graham bread with mixed die) . 

do 






90.9 


96. 3 


97. H 


82. 4 


92.9 


448 
449 


87!l 

90. G 


95.9 
93.7 
95.6 


94.9 


77.2 

77.7 


90.0 


450 


W.H.E... 


do 


'.«• 7 




Averageof 3experiinint- . 






SO. 1 


95. 1 


91.8 


79.0 


90.0 



As already stated, experiments Nos. 442-450 were intended to show 
the relative rather than the absolute digestibility of the three kind- of 
bread, and the coefficients of digestibility are therefore computed for 

the whole diet, in which the bread was the chief variant. A- might 
be expected, the range of variation in these coefficients is not as great 

as in experiments Nos. 431-441, in which the quantities of bread eaten 
formed a larger proportion of the total diet. Nevertheless the results 
stand in a similar relation to one another, the white-bread ration 
proving most digestible: in the present series, however, the ration 
with Graham bread was least digestible, while that with entire-wheat 
bread occupied rather an intermediate position. It will be noted that 
the difference between the white and entire-wheat bread ration- i- less 
than that between the latter and the Graham bread ration. 



DETAILS OF DIGESTION EXPERIMENTS NOS. 451-462. 

The present series of experiments, Nos. 4.M-4»'»l\ were made with 
flours ground from soft winter wheat. It was intended that the 
experiments in this series should be as nearly :i- possible :i repetition 
of experiments Nos. 442 150, except for the difference in the kind- of 
wheat from which the flours were ground; but it was found that the 
Graham flour provided for this series of experiments, probably through 
some carelessness on the part of the miller, contained a considerable 
quantity of corn meal. Experiments with the Graham flour were 
accordingly not made. Later developments also led to some doubt as 

to the purity of the entire-wheat flours and. though digestion experi- 
ments with bread made from them were carried out. the results 
obtained with these entire-wheat breads should not. therefore, be too 
strictly compared with those from experiments with bread from 
entire-wheat flour of known quality. 



43 

With these exceptions and the slight differences in the composition 
of the breads from day to day; the food materials used in this series 
of digestion experiments were of practically the same character as 
those used in experiments Xos. 442-450. One of the subjects was an 
assistant chemist of the experiment station, who took part in the 
experiments of the previous series; the other two were students who 
had not before been the subjects of digestion experiments. The 
results of the experiments are given in the following tables, which 
require no explanation, since they are like those already given. 



DIGESTION EXPERIMENT NO. 451. 

Kind of food. — Entire-wheat bread, beef, chicken, potatoes, etc. 
Subject.— E. F. B. 

Weight (without clothing). — At beginning, 139.5 pounds; at end, 
137.5 pounds. 

Duration. — Four days, February 17-20, 1902. 

Table 28. — Results of digestion experiment No. 451. 



Sample 
number. 




Weight 
of ma- 
terial. 


Total 
organic 
matter. 


Protein 
(NX6.25). 


Fat. 


Carbo- 
hy- 
drates. 


Ash. 


Energy. 


6632 


Bread, entire-wheat 

Beef 


Grams. 

2,295 
680 
300 

1,080 


Grams. 

1.297.5 
159. 7 
121.6 
263.9 
177 


Grams. 
169.7 
151.6 
83.3 
27.5 
L8 
1.6 
11.1 


Grams. 
7.8 
8.1 

A 

173.4 

"'ii'9' 


Grams. 
1,120.0 

"236.'6' 

1.8 

72.5 

15.6 

200.0 


Grams. 
41.5 
30.8 
6.7 
10.6 
4.2 
2.1 
2.1 


Calories. 
5,340 


6636 






6637 


Potatoes 


1,095 

1,478 

358 

215 

792 


6639 


Peaches 

Milk 

Sugar 

Total 

Feces — . 


520 j 74.1 
300 39.6 
200 200.0 












2,333.4 


446.6 


240.9 1,645.9 


98.0 


10,995 




W-4 


45.6 
401.0 
87.79 


16.2 22.6 
224.7 1-fl2S-3 


13.0 
85.0 
86.74 


540 
10,455 








93.28 


98.63 








459 




Energy oi food oxidized in 


r 








9,996 






::::::::: ::::::::::::::::::: 








90.91 






1 i 











During this experiment the subject eliminated 5,081 grams urine 
containing 56.3 grams nitrogen. This makes the average nitrogen 
balance per day as follows: Income in food, 17.9 grams: outgo in 
urine, 14.1 grams, and in feces, l.S grams; making a gain of 2 grams 
nitrogen, corresponding to 12.5 grams protein. 

DIGESTION EXPERIMENT NO. 452. 

Kind of food. — Entire-wheat bread, beef, chicken, potatoes, etc. 
Subject.-^. R. M. 

Weight (without clothing). — At beginning, 141.5 pounds: at end, 
137.8 pounds. 

Duration. — Four days. February L7-20, 1902. 



44 



Tablk 26.— Rendu of (ligation t vperimeni X 



Sample 
number. 




Weight 
of ma- 

l.-riiil. 


Total 
organic 
matter. 


Protein 


Kut. 


Carbo- 

i.y- 






6633 


Bread, entire-wheat 

Beef 


Oram. 

■j. -.".hi.:, 

800 

1,080 

200 
620 
300 
200 


Urn my. 

1,811.2 
159.7 
121.6 

177.M 
71.1 

200.0 


168 B 
151.6 

1 - 
1.6 

11.1 


drum*. 
B. i 
B. l 

. i 
17::. 1 


L.184.0 

1.8 
200.0 


11.7 

10.6 

2.1 
2.1 


1 


6636 












6638 












Milk 


at 






















•145. 7 


241.5 


1 . 669. 9 


101.2 


11 297 












84.8 


43.7 
102.0 
90 19 


10.4 
281.1 


21. K 


8.9 


409 






- 
















436 




Energy of food oxidized in 











10,392 




















1 











During this experiment the subject eliminated 5,199 grams urine 
containing 47 grains nitrogen. This makes the average nitrogen bal- 
ance per day as follows: Income in food, 17.8 grams; outgo in urine. 
11.7 grams, and in feces, 1.7 grams; makings gain of 4.4 grain- nitro- 
gen, corresponding to 27.5 grams protein. 

DIGESTION EXPERIMENT NO. 453. 



Kind of food. — Entire-wheat bread, beef, chicken, potatoes, etc, 
Subject.— E. E. N. 

Weight (without clothing). — At beginning, L61 pounds; at end. 
159.5 pounds. 

Duration. — Four days, February 17-20, L903. 

Table 30. — Result) of digestion experiment X 



Sample 
number. 




Weight 
of ma- 
terial. 


Total 
organic 
matter. 


Protein 


Pat 


Carbo- 
hy- 


A-h. 




6634 
6035 


Bread, enHre-wheat 

Beef 


Qrame. 

2, 299. 5 

680 

300 
1,080 

200 

620 

300 

200 


Grams. 

1,291.0 
159.7 
121.6 
263.9 
177.0 

71.1 
39.6 
200.0 


Qranu. 
167.1 
161.6 

- 

1.8 
1.6 

11.1 


- 
- i 

. i 

17::. 1 

'"ij.V 


1,115.6 

200.0 


17.1 

- 

10.6 

2.1 

2.1 




6636 




s. IS 


6687 






6638 






6639 








Milk 












Total 










.-, :;>.. ... 


444.0 


241.4 


1,641.5 


108.6 






Feces 






6642 


84.1 





40.7 
90.83 


13.1 


20.5 


9.H 


469 




















537 




Energy ol f<x>-i oxidized In 










10,206 




Per cent of energy utiiiz<-<i. 










91.02 








1 







15 

During this experiment the subject eliminated 5,304 grams urine 
containing 59 grams nitrogen. This makes the average nitrogen bal- 
ance per day as follows: Income in food. 17.7 grams: outgo in urine, 
14.7 grams, and in feces. 1.6 grams: making a gain of 1.4 grams 
nitrogen, corresponding to 8.7 grams protein. 

DIGESTION EXPEKENIENT NO. 454. 

Kind of food. — Blended-flour bread, beef, chicken, potatoes, etc. 
Subject.- E. F. B. 

Weight (without clothing). — At beginning. 138 pounds; at end, 138 
pounds. 

Duration. — Four days. February 21-27, 1902. 

Table 31. — Results of digestion experiment No. 4?4- 



Sample 
number. 



. Weight Total p rr , rpin Carbo- 

of mate- organic ,£ °l e £C Fat. hv- 
(NX6.25). drates. 



Bread, blended-flour. 

Beef 

Chicken 

Potatoes 

Butter 

Peaches 

Milk 

; Sugar 

Total 



Grams. Grams. 



.2&2 1. 

- 
300 i 



Feces 

Amount digested 

Per cent digested 

Estimated energy of urine. . 
Energy of food oxidized in 

the body 

Per cent of energy utilized. . 



159. 7 
121. 6 
263.9 
177.0 
71.1 

2oo!o 



Grams. 
119.1 
151. 6 
83.3 
27.5 
1.8 
1.6 
11.1 



Grams. 
10.1 
8.1 



Grams. 
1, 109. 4 



■126. 213. 5 



236.0 
1.8 
72. 5 
15.6 

200.0 



Grams. 

30!8 
6.7 

10.6 
4.2 
2.1 
2.1 



■3 



11.1 
384.6 

90.2.S 



14.3 19.6 
229.2 ;i,615.7 

94. IS ?S. *C 



11.5 
84.4 



476 
10,642 



10.222 
91.94 



During this experiment the subject eliminated 5.011 grams urine 
containing 16.2 grams nitrogen. This makes the average nitrogen 
balance per day as follows: Income in food. 17 grams: outgo in 
urine, 11.5, and in feces. 1.6 grams: making a gain of 3.9 grams nitro- 
gen, corresponding to 21.1 grams protein. 

DIGESTION EXPEKLMENT NO. 155. 



Kind of food. — Blended-flour bread, beef, chicken, potatoes, etc. 
Subject.— E. R. M. 

Weight [without clothing). — At beginning. 139.8 pounds: at end, 
138 pound-. 
Duration. — Four days, February 34-27, 1902. 



4<» 



Table '■'.-. — Results of digestion experiment .v 



Sample 
Dumber. 




Weight 

Of ma- 
terial. 


Total 
organic 
matter. 


Protein 


I ..i 


Carbo- 

hy 
dratm. 


Ajfa. 


Kntivy. 


6656 
6635 


Bread, blended-flour 

Beef 


Qranu. 
2,284.6 

300 
1,080 
200 
620 
300 
200 


Qranu, 
1,270.8 
169.7 
121.6 
268.9 
177. (P 
71.1 
89.6 
200.0 


Grams. 
161.7 
161.6 

L8 
1.6 

il.i 


drum*. 

9.1 
B. i 

. i 
17::. 1 

"iiV 


1,109.5 

1.8 

200.0 


groan. 

u i 

10 t. 
2. 1 


909 




















6689 








Milk 












Total 










2,806.2 


•lis. t; 


242.2 


1,685. 4 


'.i7.'.. 


10,088 










93.8 




60.0 
B8.S4 


10.7 
281.6 


22.7 


10.4 


417 
























337 




Energy of food oxidized In 









































The urine eliminated on the fourth day was lost. During the lir>t 
three days the urine amounted to 4,094 grams and contained 32.4 grama 

nitrogen. Average nitrogen balance per day: [ncome in food, 17.1 
grams; outgo in urine. 11.1 grams, and in feces, 2 grams; making a gain 
of 4 grams nitrogen, corresponding to '25 grams protein. 

DIGESTION EXPERIMENT BTO. 466. 



Kind <>f food. — Blended-flour bread, beef, chicken, potatoes, etc 
Subject— E. E. N. 

Weight {without clothing). — At beginning. L58.7 pounds; at end. 1.M.7 
pounds. 

Duration. — Four days, February 24-i'T. l!)<>2. 

Tabi.k 33. — Results of digestion experiment No. +56. 



Sample 
number. 




Weight 

of ma- 
terial. 


Total 
organic 
matter. 


Protein 


rat 


Carbo- 
hy- 
drates. 


Aah. 


Energy. 


6657 
6535 


Bread, blended-flour 

Beef 


Qranu. 

680 

300 

1,080 

200 

300 
200 


Qranu. 

1 . 282. - 
158.7 
121.6 

177.0 

71. 1 

200.0 


Qranu. 

1 IB. •.' 
151.6 

1.8 

i. a 

n.i 


Qranu 

8. 1 

. I 
178. i 

"ij.Y 


Qranu. 
1,124.0 

1.8 
16.6 


Qranu. 

2.1 
2.1 




6636 
















1. 178 


6639 








Milk 


J 15 










Total 










2,818.7 


426.8 


242.0 


1,649.9 


99.3 


11.117 




70.8 




3*. 3 


10.8 
j::i 2 
95.53 


14.2 
99. 1 1 


7.5 
9L8 


407 






10.710 
























Energy of food oxidised In 














10.036 







































47 

Daring this experiment the subject eliminated 7.299 grams urine 
containing 57 grams nitrogen. This makes the average nitrogen 
balance per day as follows: Income in food, 17.1 grams: outgo in 
urine. 14.2 grams, and in feces, 1.5 grams; making a gain of 1.4 grams 
nitrogen, corresponding to 8.7 grams protein. 

DIGESTION EXPEKIMEXT NO. 457. 

Kind of food. — Entire-wheat bread, beef, chicken, potatoes, etc. 
Subject.— E. F. B. 

Weight {{without clothing). — At beginning. 136 pounds: at end, 135.5 
pounds. 

Duration. — Four days. March 3-6, 1902. 

Table 34. — Ile.vj!t$ of digestion experiment No. 4o7. 



Sample 
number. 




Weignt 
of ma- 
terial. 


Total 
organic- 
matter. 


Protein 
(N <6.25). 


Carbo- 
Fat. hy- 
drates. 


Ash. 


Energy. 


6673 


Bread, entire-wheat 

Beef . . 


Grams. 
2,326.5 

680 

300 

1,080 

200 
520 
300 
200 


Grams. 

1,268.1 
163.6 
120.9 
246.3 
176.9 
74.1 
39.6 
200.0 


Grams. 
164.2 
151. 4 
84.7 
26.8 
2.2 
1.6 
11.1 


Gram*. Grams. 
8.1 1,095.8 

12.2 

36.2 ! 

.6 218.9 
172.9 I 1.8 

72.5 

12.9 15.6 


Grams. 
45.4 
28.1 
6.2 
10.5 
4.2 
2.1 
2.1 


Calories. 
5. 443 


6677 










1,036 
1,482 






6639 






Milk 












Total 












2.289.5 


442.0 


242.9 1,604.6 


9*. 6 


11,077 


6680 


70.0 




32. 5 
409.5 
92.65 


11.6 ' 16.4 
231.3 1,588.2 
95. 23 - - 


9.5 
89.1 
90.31 








10,691 






















Energy of food oxidized in 




10,161 




Per cent of energy utilized . 





















During this experiment the subject eliminated 4,801 grams urine 
containing 48.1 grams nitrogen. This makes the average nitrogen 
balance per day as follows: Income in food. 17. 7 grams: outgo in urine. 
12 grams, and in feces. 1.3 grams; making a gain of 4.4 grams nitrogen, 
corresponding to 27.5 grams protein. 



DIGESTION EXPEKIMEXT XO. 458. 

Kind of food. — Entire-wheat bread, beef, chicken, potatoes, etc. 
Subject.— E. R. M. 

Weight (without clothing). — At beginning. 139 pounds: at end, 
136 pounds. 
Duration. — Four days, March 3-6, 1902. 



48 



Table 35. — Results of digestion experiment \ 



Sample 
Dumber. 




Weight 
of ma- 
terial. 


Total 
organic 
matter. 


Protein 


Fat. 


Carbo- 

, h - v 

drill.-. 


V-li. 


1 II. TKY. 


6674 
667(1 


Bread, entire-wheat 

Beef 


Grams. 

680 
300 
1,080 
200 
620 
300 
200 


Grama. 
1,298.6 
168.6 
120.9 
246.8 
176.9 
74.1 
99.6 
200.0 


Grams. 

l.M. 1 

M.7 

•J.J 
1.6 
11.1 


Gram*. 

12.2 

.6 
172.9 

"ij.'y" 


Grams. 

1,114.8 

"ai'o 

l 8 


dm ins. 
1 J 

21 

2.1 


' iiluriiK. 


6677 
















1. Kfl 










Milk 












Total 












2,815.0 


146. 7 


241.7 1,628.6 


«.»S.7 


11.219 




Feces 






6681 


115.2 




60.1 

- 


12.1 I 31.5 
1.582.1 


11.6 










95.03 












541 




Energy of food oxidized in 










10,00 





























During this experiment the subject eliminated 5,296 grama urine 

containing 40.7 grams nitrogen. This makes the average nitrogen bal- 
ance per daj T as follows: Income in food. IT.'.' grams; outgo in urine. 
10.2 grams, and in feces, 2.4 grams: making a gain of .'».."> grams nitro- 
gen, corresponding to 33.1 grams protein. 

DIGESTION EXPERIMENT NO. 459. 

Kind of food. — Entire-wheat bread, beef, chicken, potatoes, etc. 
Subject.— E. E. N. 

Weight {without clothing). — At beginning, 156 pounds; at end. 
155.7 pounds. 

Duration. — Four da vs. March 3-6, 11)02. 



Table 



-Results of digestion experiment A 



Sample 
number. 




Weight 

of ma- 
terial. 


Total 

organie 

matter. 


Protein 


Fat. 


Carbo- 

hy- 


A-li. 


lii.TK-y. 


6675 
6676 


Bread, entire-w heat 

Beef 


drams. 

2,844.6 

680 
300 
1,080 
200 
520 
300 
200 


Grams. 

1,288.8 

L68.6 

120.9 

L76.9 

71.1 
200.0 


Grams. 
157 B 
161. i 
B4.7 

2. J 

L6 

ll.l 


Grams 
12.3 

"ij.V 


Grams. 
1,116.6 

"218.*9 : 
L8 

16.6 

200.0 


dlH Ills. 
Ill 

I.J 

2.1 

J. 1 




6677 






6678 






6679 






6639 








Milk 






















2,804.7 


435.6 




1 . 625. 1 


97.3 












6882 


82.5 




39.8 


13.1 


19.7 
1,606.7 


9.9 






























Energy of food oxidized in 

















































49 



During this experiment the subject eliminated 5,984 grams urine 
containing 46 grams nitrogen. This makes the average nitrogen bal- 
ance per day as follows: Income in food. 17.1 grams; outgo in urine 
11.5 grams, and in feces, 1.6 grams: making a gain of 1.3 grams nitro- 
gen, corresponding to 26.9 grams protein. 

DIGESTION EXPEEEMEXT NO. 460. 

Kind of food. — Blended-nour bread, with beef, chicken, potatoes. 
Subject.— &. F. B. 

Weight {without cloth''/"/). — At beginning. 131.5 pounds: at end, 135 
pounds. 

Duration.— Four days, March 10-13, 1902. 

Table 37. — }'e-<n!ts of digestion experiment No. 460. 



Sample 
number. 




Weight 
of ma- 
terial. 


Total 
organic- 
matter. 


Protein 

-" 


Fat. 


Carbo- 
drates. 


Ash. 


Energy. 


6695 


Bread, blended-flour 

Beef 


Grams. 

2,302.5 

680 

300 
1,080 

200 

520 

300 

200 


Grams. 

1,278.1 
163.6 
120.9 

■i±;.z 

176.9 

-74.1 

39.6 

200.0 


■ 
150.8 
151. 4 
84.7 
26.8 
2.1! 
L6 
11.1 


Gram*. 

6.9 

12.2 

36.2 

.6 

172.9 

"iiY 


Grams. 

1,120.4 

"218.9 

1.8 

72.5 

15.6 

200:0 


Grams. 
41.2 
28.1 
6.2 
10.5 
4.2 
2.1 
2.1 


Calories. 

5,446 

945 






806 






1,036 

i. :-. 


6679 








358 




Milk 


215 
























2,299.5 


42S.6 


241.7 1,629.2 


94.4 


: i - 




Feces — . . . . , 




6698 


44.7 




21. 5 
407.1 
94.98 


7.1 
234.6 
97.06 


10.0 

1,619.2 

99.39 


6.1 
88.3 
93.54 


247 
10,833 










526 




Energy of food oxidized in 








10,307 




Per cent of energy utilized . 



























Daring this experiment the subject eliminated 4,741 grams urine 
containing 49.2 grams nitrogen. This makes the average nitrogen 
balance per day as follows: Income in food, 17.1 grams: outgo in 
urine 12.3 grams, and in feces, ". v gram; making a gain of 1 grams. 
corresponding to 25 grams protein. 

DIGESTION" EXPERIMENT XO. 461. 

Kind of food. — Blended-flour bread, with beef, chicken, potatoes. 
Subject.— E. R. M. 

Weight {without clothing). — At beginning, 136.3 pound-: at end, 135 
pounds. 

Duration.— -Four days, March 10-13. 1902. 



2167 



-No. 143—04- 



50 



Tablb 38. — Results of digestion experiment No. f6I. 



Sample 
Dumber. 




Weight 

of ma- 
terial. 


Total 
organic 
matter. 


Protein 


Fat. 


i.irl...- 

hy- 
d rates. 


Ash. 




6696 


Bread, blended-flour 

Beef 


680 

:5oo 

1,080 

200 

300 
200 


Grams. 

1,291.9 
168.6 
120.9 

17.,'.. 
71.1 


Grama. 
168.7 
16L i 
84.7 
26.8 

1.6 

ll.l 


7... 

1 J. 2 

L72.9 


'■jiv'-y 

200.0 


2.1 
2.1 




















1 ej 










Milk 






Sugar 

Total 
















2,318.8 


4:50. 5 


211. 8 1,641.0 


93.1 


11,147 










91.5 




49.1 
881. i 


11.1 21 4 


9.9 


614 






95. 1 1 


1,619 6 


















Energy of food oxidized in 










in 148 












90 M 















During this experiment the subject eliminated 5,238 grama urine 
containing 45.1 grams nitrogen. This makes the nitrogen balance per 
day as follows: Income in food. 17.2 grams; outgo in urine, 11.3 

grams, and in feces, 1.9 grams: making a gain of 4 gram-, corre- 
sponding to 25 grams protein. 

DIGESTION EXPERIMENT NO. 462. 

Kind of food. — Blended-tlour bread, with beef, chicken, potatoes, etc. 
Subject.— E. E. N. 

Weight (without clothing). At beginning. L57.0 pounds; at end, 
15.5. T pounds. 
Duration.— Four days, .March 10-13, 1902. 

Table 39. — Results of dig* sHon experiment No. 462. 



Sample 
Dumber. 


Weight 

Of ma- 
terial. 


Total 
organic 
matter. 


Protein 


Carl-.- 
Fat. hy- 
drate*. 




Energy. 


6697 
6676 


Bread, blended-flonr 

Beef 


Grams. 

2,819 

- 

300 

1,080 

200 

520 

300 

200 


Grams. 
1,289.5 

120.9 

170.'.' 
71. 1 


Grams, 

l : 
161. 1 
84.7 

L6 

11.1 


Gramt. ■ 

12.2 



.6 Jlv.< 
172.9 1.8 




in 5 

2 1 
J. 1 






















6689 








Milk 










200.0 






Total 













2,810 9 




240.8 1,641.6 


93.8 


11. .'it". 










6700 


47.7 




23.3 


7.3 11.3 


6.8 
































Energy of food oxidized In 














UlM 




Per cent of energy utilized . 

































During this experiment the mbjed eliminated 6,178 grams unrine 

containing 52.4 gram- nitrogen. This make- the average nitrogen 



51 

balance per day as follows: Income in food, 17.1 grams: outgo in 
urine. 13.1 grams, and in feces, 0.9 gram; making a gain of 3.1 grams, 
corresponding to 19.4 grams protein. 

SUMMARY OF RESULTS. 

The following table summarizes the results of experiments Nos. 151- 
162: 

Table 40. — Summary of experiments Xos. 451-462 — Digestibility of nutrients ore! avail- 
ability of em rgy. 



Ex- 
peri 
ment 




Coefficients of digestibility. 



Kind of food. 



Protein. Fat. 



Carbo- 
hydrates. 



Avail- 
ability of 
energy. 



P.M. 
E.N.. 



P.M. 
E.N.. 



R.M. 

E.N.. 



Mixed diet, including entire- 
wheat bread. 



Average of 3 experiments. 

Mixed diet, including white 
bread. 



Average of 3 experiments. 

Mixed diet, including entire- 
wheat bread. 

....do 

do 



Average of 3 experiments 

Mixed diet, including white 
bread. 

....do 

....do 



Average of 3 experiments 



Per cent. 
89.79 



Per cent. 
93.28 



95.69 
94. 57 



Per cent. 
98.63 

98.69 
98.75 



Per cent. 
86.74 



91.20 
90.54 



98.85 J 



90.02 94.96 



9S.06 
98.79 



98.70 
99.31 



59.83 



89.50 



93.54 

89.36 
93. 81 



92.24 



91.30 
~9l794 



91.80 

91.73 

89.52 
90.52 

90.59 

93.02 



90.99 
91.90 



The differences in average digestibility with the two grades of flour 
were small. No conclusion is warranted from a comparison of the 
results, however, because as was stilted there were reasons for believing 
that the whole-wheat flours were not what they purported to be. The 
results summarized in the table above are therefore not discussed. 

GENERAL SUMMARY. 

The following table summarizes some of the result- obtained in 
experiments carried out at this station to Irani the relative digestibil- 
ity of Graham, whole-wheat, and patent Hour bread, including not only 
the experiments reported in detail in this bulletin but also for purposes 
of comparison the 21 reported earlier. The data here given include 



"l\ s. Dept. A-r.. Office of Experiment Stations Bui. S5. 



52 

the proportion of the total protein and energy of the diet thai was rap- 
plied by the br« id, the coefficients of digestibility of the nutrients of 
the total diet, and. in the last two columns, the proportion of the total 
energy that was actually available to the body. These last values are 
computed in two way-. In the next to the last column the energy lost 
in the urine is calculated as described on pages 20 and 21, where it i- 
assumed that the average heat of combustion <<l tin- organic matter of 
the urine corresponding to 1 gram of digested protein amounts to L.26 
calories. Since samples of urine were collected in all but the first 
24 of these experiments, and the heat of combustion was actually 
determined in all cases, data are available for calculating the available 
energy of each experiment on an independent basis, and the results 
thus obtained are given in the last column. 

If this organic matter of tin- urine were derived entirely from the 
food under investigation, the results obtained by the second method 
should, of course, be given the preference. A- noted elsewhere (pp. 
13 and 56), the "nitrogen Lag" makes it impossible to trace any exact 
relation between the protein of the food eaten on a given day and the 
nitrogen in the urine. It may be, therefore, that the results obtained 
by the use of a definite factor, representing the average of a large 
number of determination.-, gives as accurate results a- can be obtained 
at present. 



53 



;s i 






- i — ' -6 -, — — ' — si x" si = x' =' - i — : — ' - i :-:' :s :-. -i ~ — ' .-' ..-' — — — —'•: i si cr." si re x' 
r- r- r- s. ~ r ~ x x a z. x s. - s. ~ - s. ~. z. r. r. s. z. z z z. z. z. z. x z. x z- x 



: --. cs -.-. x - : : z- ■ - 



:r.*.M^s^r./.r^^r:'C':ix^ ..■: c -/. ^ i^ - ?i c - : i v; i- x ic go s. 

: x x' i- x x i-'i-'i- —'— ' — '■ ■--. ■£ r~i- x x" x x'i- x :- — ' x s.' x x'i- .-' -iri-'ti x — ' 
; r. s. s. — s- — z- z. z- z. z- z. z. z. z. z. z. z. z. z. z- z- z- z. z. z- z. z- z. z. z- — z. s. z. 



)OiOCHD<B<MT(l^HI>iO<NO)HCOtDriM100tt>iOOaiOt-OOOtO(NOaOO>r1 

!.-' r-i:^ si si — X — ' — ' ■£ — :-* I- --C X — ' X x' [- X --i :~ si x' X / - -' • -' .-' I - -' .-' — ' 

: -z. vr. -- x s. zr. x - - - z. z. z. z. z. z. z. z. z. z. z. z. z. z. z. - z. z. z. z. s- s. s. s. 



x s. S. x x x - x x 



. X X X X X X X X 



~J x ic — r~ cm ac lz. c. ■ 

C si S". s^. s. si si si s. 



: ss ? ; :-: x i~ r- x -r — — -.s ec 



•-S X : - : - : - - ; - 

■ z- z. z. z- z. z. z. s. 



:_; — f x - x .-.:-._; 7 t_ : -s :-. 



:.-- u~ s 



^iSiB^is^^^^-^ 






- ■ £ ' = 

-c-z::r:c::-c:.:t:- 

— — 1 — - — — ~ — — — ~r - 



3 O ffl ffl O O g O O 3 O O « 

s— — —- — —- — ——' 



- — — —- — — — .- — — - — — — .- — jz — — - — —- — — — — - 



-/. x i. •/. .-. rz i. x u. r -_ - ■_ - : 






--^i 



,7l?,f,:M,f^] 



- 



r>4 



-1 



P" 8 



- 



; r. r- r- - 5 ."■ / 7 / f. r. s 5 r. 3 r" 5- 3 S r. r. 



-j ti i- ti .^ ?i -c -n r r- 1 - -i - : 



■•a 



~: ?i = ?i x i- - - s r. - i- x /■ - _ 3 _ / - i- do 



j : r. /• r. - — -/- - r - « :-. i - -^ — <e .- : i - ■- = 

; r- c- ~. ~ c. r- r- r- r. r. r. r- r r. r- r r 



BgSS3§38Sg88§ i > 7- 



: ^ S3 

- =r 
3 = = 



*i at /• s / r- - r 5 o a>ooo>a> o> o> c ~ - r. r 

_ — - - - - — - - — ,- ,- 



mm 



^.'i-.-.-ririn ■-. / 1 /.-.-■-;- 

5 :-.:::: 



* 



: c = ; : 

— — ^-- 

: := : : 






^ ~ - = 






55 

Some interesting deductions may be drawn from the data summa- 
rized in Table 11. It is evident that, in general, the nutrients of 
bread when eaten alone were not as completely digested as when the 
bread was eaten with milk. It is also noticeable that the coefficients 
of digestibility of the nutrients of a more varied diet, including large 
proportions of bread, were not greater on the average than those 
obtained with a simple ration of bread and milk. 

In general, the digestibility of the ration, whether simply bread and 
milk with a little butter and sugar or a more varied diet, was decreased 
when the change was made from white bread to entire-wheat bread, 
and still further decreased when either was replaced by Graham bread, 
the remainder of the diet being, of course, the same in all three cases. 
The differences are sufficient to indicate that, even though the Graham 
flour contains the most and the white flour the least total protein of 
the three, the body would obtain more protein and energy from a 
pound of entire wheat than from a pound of Graham flour, and still 
more from a pound of white flour than from either of the others. 

On the other hand, it does not follow from this that a larger amount 
of digestible nutrients or available energy may not be obtained from 
100 pounds of wheat when milled as Graham flour or entire-wheat flour 
than when ground into patent flour, because 100 pounds of cleaned 
and screened wheat will yield 100 pounds of Graham flour, about 85 
pounds of entire-wheat flour, and only a little over "i'2 pounds of 
standard patent flour. This, however, is a question of pecuniary 
economy, which would be more appropriately discussed elsewhere. 

From all the data included in this bulletin and in others reporting 
previous work on the same subject, it is evident that all kinds of wheat 
bread are quite well digested and worthy of the important place in the 
diet whicli they hold. In fact, there is no single food which is so 
indispensable as bread. It is a very economical source of nutriment, 
and the different kinds are valuable as affording means "for variety in 
the diet. 

INCOME AND OUTGO OF NITROGEN. 

The following table summarizes the data regarding the income of 
nitrogen in the food, the outgo in the feces and urine, and the gain or 
loss by the body in the digestion experiments with different kinds 
of bread reported on preceding pages. The figures in each case rep- 
resent the total quantities for an experiment. 



56 



Table }■_'. — Income nml outgo of tiiir<»/itt in digestion < vpcrimenl 



Kx- 


Subject. 

P.H.M ... 

.1. <'. T .... 


Kind of food. 


Inira- 

tion. 


Nitrogen. 


menl 

num- 
ber. 


In food. 


In urine. 




«.r 


431 
432 


White bread, with milk, batter, 
and sugar. 


1 M ;/.-'. 

2 

•J 
2 

•-' 

•_' 

■J 
2 

2 

•1 
■l 

2 
4 

4 
1 
4 

4 
4 
4 

1 

! 

4 

I 
1 

1 

! 

4 

1 
1 

1 
1 


Grams. 

22.7 
24.6 
82.0 

21. 1 
19.6 

20.5 

•J1.7 
17.0 

in. 7 

82.70 

83.06 
82. 59 
89.71 

89.60 
89.20 

93.04 

93.31 
92,51 

71.5 

71.:'. 
71.0 

70.7 

71.:. 
69. 7 


l'.e 1 
•J7.7 
18.6 

lv 1 
J 1.1 

.v.. 1 

18.0 

59.74 

62 71 
66. 1 1 

17.11 
17.0 


9.69 

11.99 

7. in 


0.9 


433 
434 

435 


W. li.W .. 
P.H.M... 

J.C.T .... 


do 

Entire- wheat bread, milk, butter, 
and sugar. 


0.1 


436 

437 

438 


W. B. W . . 
P.H.M ... 

J.C.T 


do 

Qrabam bread, milk, butter, and 
sugar. 


- 0.6 


439 
440 

441 


W.B.W .. 
P.H.M ... 

J.C.T .... 


do 

White bread, milk, butter, and 
sugar. 


'.' 1 


442 


E.R.M ... 

.1 B. F 


Mixed diet, including white 

bread. 
....do 


• 1'.'. 1'.' 


444 

445 


W. it. E... 
K. B. M . . . 

J.E.F 


do 

Mixed diet, including entire- 
wheat bread. 
do.. 


• .'1.1.' 


447 
448 


W.II.K... 
E.R.M ... 

J.EJ .. 


do 

Mixed diet, including Graham 
bread. 
do 




450 
451 

452 


W.H.E... 

E. F. B .... 

E.R.M ... 
E.E.N.... 
E. F. K . . . . 

E. II. M ... 
E. E. N. . .. 
E. F. B . . . . 

E.R.M ... 
E. E. N . . . . 
E. F. B.„. 

E.R.M ... 
E. E. N . . . . 


.....do........ 

wheat bread. 
do 




453 


....do... 




454 

455 


Mixed diet, including white 

bread. 
....do... 




457 

458 


do 

Mixed diet, including entire- 

u heat bread. 
....do... 


57.0 

1- 1 

in 7 

15. I 
52. 1 


17 1 

+16.0 


459 
460 

4G1 


do 

Mixed diet, including white 
bread. 


462 


....do... 











In tin- experiments in which the die! consisted almost wholly of 
bread and milt there was in all hut a few cases <>nl\ a small difference 

between the nitrogen in the f 1 consumed and thai in the excretory 

products. In the experiments with mixed diet, on the other hand, in 
all but four cases the differences were larger. It i- noticeable, t<>... 
that in the former experiments there was in Borne cases a gain and in 

others a loss of nitrogen. I nit in the latter there was a gain of nitrogen 
in every case. It will be observed that the income of nitrogen \\:i- 
much larger in all the experiments with mixed diet than in those with 
the more simple diet. Since nothing was known concerning the con 
ditions of income and outgo of nitrogen with the subjects preceding 
the experimental periods, it is impossible t<> tell jusl in how far tin* 
nitrogen of the urine collected during the experiments represents 
that of the food consumed, because of uncertainty regarding the 
lag of excretion of nitrogen pertaining t<> the food previous to that 
of the experiments. Late investigations carried on l>y 1'. 1'.. Hawk 



"Aiucr. Jour. Physiol., L0 | 1903), p. L16. 



57 

indicate that an increase of nitrogen in the food is eliminated in the 
urine in a comparatively short time. It may perhaps be fair to assume 
that at least in the experiments with mixed diet, which were of longer 
duration than the others, there was some relation between the nitrogen 
of the food and that of the urine. That being the case, the results 
would indicate that the diet in these experiments, which contained 
large proportions of bread, was more than sufficient to meet the bodily 
needs of the subjects for protein, so that in each instance there was a 
storage of protein. This was true whether the diet contained white, 
entire-wheat, or Graham bread, no differences being observed that 
could be attributed to different sorts of bread. 

METABOLIC PRODUCTS IN FECES. 

It has been noted that in harmony with the general custom the 
digestibility in these experiments was determined in accordance with 
the assumption that the feces consist entirely of undigested residue. It 
is well known, however, that they contain, in addition to such material, 
considerable amounts of various waste substances — the so-called meta- 
bolic products — consisting of residues from the bile, mucus, saliva, 
gastric juice, pancreatic juice, and other digestive secretions, small 
portions of the mucous membrane lining the intestine, debris from the 
walls of the stomach, etc. The results of recent investigations indicate 
that the proportion of metabolic products in the feces is larger than 
was forinerlj- supposed, and that for man}' foods, provided there has 
been careful preparation and proper mastication, digestion is quite 
complete, the undigested residues in the feces being accidental rather 
than incidental. Much study is now being given to this subject, and 
attempts are made by chemical and microscopical methods to deter- 
mine the amounts of metabolic products excreted daih* in the feces, 
inasmuch as such data are necessaiy before estimates of the actual 
digestibility of food materials can be made. In a former bulletin 
reporting experiments at the Maine Station some of the more impor- 
tant investigations were mentioned. 

In general it may be said that of the several chemical methods thus 
far proposed for separating the undigested material from the other 
products the following have seemed most promising, namely, one in 
which the attempt is made to dissolve the metabolic products of the 
feces by pepsin or other ferments, leaving the undigested residue of 
the food, and the other, in which the attempt is made to dissolve out 
the metabolic products by treatment with one or more solvents, like- 
wise leaving the undigested residue behind. 

In view of the importance of such work, studies of the amounts of 
metabolic nitrogen in the feces have been carried on as a part of the 
investigation of the nutritive values of bread at the Maine Experiment 
Station, and the results of such studies made in connection with the 



58 

digestion experiments reported in this bulletin are reported in the 
following pages, but simply as a contribution to the knowledge of the 
subject, without any extended discussion. The methods employed in 
these studio were ( l ) treatment of the feces with pepsin solution, and 
(2) treatment with ether, alcohol, hot water, and cold limewater. 

TREATMENT <>F FECES with PEF8TN. 

A- in earlier experiments at the Maine Experiment Station" a weighed 
portion of the finely ground I'eees from each digestion experiment was 
treated according to the usual method with a pepsin solution prepared 
by dissolving L.25 grams of German plain soluble pepsin in 1 liter 
of 0.2 per cent hydrochloric acid (made by adding 20 cubic centi- 
meters of a solution containing exactly L0 per cent hydrochloric-acid 
gas to 1 liter of water) and adding .~> cubic centimeters of a solution of 
thymol in alcohol as a preservative. Two hundred cubic centimeters 
of this solution was heated to 50° C, the weighed quantity of feces 
was then added, and the beaker kept in a water bath at 40 ( '. for eight 
hours on two successive days. At intervals of two hours 1 cubic 
centimeter of 10 percent hydrochloric acid was added until the final 
strength of the solution was 0.5 per cent. On the day following the 
second period of digestion on the water bath the solution wa9 decanted 
upon folded filters. The residue was washed by decantation and also 
upon the filter until no test for proteids was obtained in the wash 
water. The filter and contents were then dried, as much as possible 
of the top of the filter was cut off, and the nitrogen in the dried 
material, which was assumed to represent the nitrogen of undigested 
material, was determined by the Kjeldahl method, a suitable correc- 
tion being made in the results for the small amount of nitrogen of 
the filter paper. The results obtained 1>\ tin- method are shown in 
Table 43. 

TREATMENT OF FECES WITH ESTHER, ALCOHOL, BOT WATER, \M' 
LIMEWATER. 

The treatment of feces by this method, which was the same in these 

experiments as in those previously reported was, in brief , as follow-: 

One gram of finely ground feces was boiled for one-half hour with •_'."» 

cubic centimeters of anhydrous ether in a small flask with a reversed 
condenser, the ether decanted upon a Biter, and the operation repeated. 

After washing with ether by decantation, 50 cubic centimeters of '.t."i 
percent alcohol was poured upon the residue of the fee- in the tla-k 

and boiled for ten minutes, a reversed condenser being used a- before. 
The alcohol was decanted upon the same filter as was used for the ether 

oTJ. s. Dept \_'i.. Office o< Experiment Stations Bo] 



59 

extract and the whole washed with hot alcohol. The sample of feces 
was then heated on a steam bath for twenty minutes with 50 cubic 
centimeters of water and the whole washed with hot water upon the 
same filter as before. Feces and filter were then placed in a beaker 
with 50 cubic centimeters of a saturated solution of limewater and 
allowed to stand for six hours, after which the whole was thoroughly 
washed upon a fresh filter with dilute limewater. The residue was then 
dried and the nitrogen in it determined by the Kjeldahl method, a 
correction being applied for the nitrogen in the filters. The results 
of experiments by this method of making correction for the metabolic 
nitrogen of feces in the digestion experiments are also shown in 
Table 43. 

The significance of the figures included in the table may be explained 
by use of the data from one of the experiments, for instance Xo. 431. 
In one method the nitrogen of metabolic products was assumed to be 
dissolved out of the feces by pepsin solution, leaving the undigested 
protein in the feces not dissolved. During the two days of this experi- 
ment the total feces, partially dried, weighed 27.8 grams and contained 
5.39 per cent or 1.50 grams of nitrogen. The portion of the feces 
not dissolved by treatment with pepsin contained 1.25 per cent of 
nitrogen, which would give 0.35 gram in the total feces as coming 
from undigested protein. Subtracting the latter from the total nitro- 
gen of the food (which was estimated as 16 per cent of the total pro- 
tein) would give (36.37—0.35=) 36.02 grams as digestible nitrogen, 
implying that 99.04 per cent of the total nitrogen was digested. Obvi- 
ously, this would also be the coefficient of digestibility of protein of the 
food as corrected for metabolic products determined by this method. 

In the other method the metabolic products were likewise assumed 
to be dissolved by treatment with the several solvents, leaving the 
undigested protein in the material not dissolved. Considering again 
the figures for experiment Xo. 431. it will be observed that the residue 
from feces not dissolved by this method contained 3.32 per cent or 
0.92 gram of nitrogen, which, subtracted from the total in the food, 
gave 35.45 grams as the amount digested, the coefficient of digest! bility 
being in this case 97.47 per cent. 

In those experiments in which the diet consisted of bread, butter, 
milk, and sugar, namely. Xos. 431-441. corresponding value- for the 
digestibility of the nitrogen from the bread alone were computed by 
proportion. As previously explained (p. 19), the protein in the feces 
due to undigested bread was calculated by assuming a factor for the 
digestibility of the protein in the rest of the diet; and the nitrogen in 
it was calculated in the usual way by attuning that the protein con- 
tained I*; per .em of this element. In order to calculate the quantity 



60 

of metabolic nitrogen <>t' the feces thai would be < 1 in- t<> bread alone, 
it was assumed thai the nitrogen in the total feces bears the same rela- 
tion to the nitrogen in the feces from bread alone thai the nitro 
not dissolved by treatment in the total feces bears to the nitrogen not 

dissolved in the feces from bread alone. Thus, in experiment No. i:;i. 
the nitrogen not dissolved by treatment with pepsin in the U'i-t"* from 
bread was 0.29 gram as computed according to the following propor- 
tion: 1.50 : 0.35 :: 1.25 : 0:29. In the same way the nitrogen in the 
feces from bread not dissolved by treatment with ether, alcohol, hot 
water, and limewater was u.77 gram ;i- computed according to the 
proportion 1.50 : 0.02 : : 1.25 : <».77. 

This is equivalent to the assumption that the metabolic products 
from the digestion of milk and other foods besides bread would con- 
stitute the same proportion of the total feces as those from the dig 
tion of bread itself. Although there is no definite warrant for this 
assumption, it seems fair to say the results can be but slightrj affected 
by considerable variations in the relative amounts, owing to the fad 
that the quantity of nitrogen in the feces from foods other than bread 
was generally considerably smaller than that from bread. 

Table 43 summarizes the figures showing the digestibility of nitro- 
gen (protein) when corrections for metabolic nitrogen in the feces art- 
introduced. 



61 



_- 


i d 


•^ -ar- 


CO O 3» O 




= 


1C 




c 






c 


1? 


t£ 


2 


g 


0- 


t~'cf 


<£ 


1-- 


001 


o 

8'-' 


<D O 


il r-^ d io co r- o 
Si- 


r-<CO 
03CO 


di> 


6t^ HX OO OiO CNOi OC-1 

ence enco 0000 oooc cs 00 x 00 


o o 

£3 


-d£° 

S - =P 


ft^ 








g -*co oo r-n. 


OCR 
OCR 


§§ 


HN OlO i-fO 040 OCO COO 

t>o> cix coo tpco r---^ c-i-r 




53 ioci t-i ic co -i< 


oio 




t^ <N -jri 06 co ai-r do d d 

Hri C0CN iHi-H r-lrH »— 1 »— 1 




o .« 






.Cd 


O c 


C! "^ ^"^ ^^ 










h 


g ot^ oo toio 


00 t^ 


as 


tcoc cor~ o^n 00 to 00 e» -* 

CO t- rHSl r-11-l (Ni-H C?» IH COCO 


•g"§ 


it 


05 








9" 


5 N 


O 


en 




c» 

CO 




g 




Oi ! r-l 


rH ! CO 


§8 


8 : 


£ 


S 


1 " 


























i d 

<u o 


g or- cir- cats 


8S 


ss 


OlO ICO OiC lOOO 1O1O iCM 
COi> I>CO OC-1 GOT r-IOl 00 


g 




" c»cn ct>cr oscr 


dio 


ss 


d ^ dd d-* T^d r^d -pk 


1 




$ 
















ft 


|'2 ^ 
,9 ~ 


g 6m coo cnco 


dio 


§s 


SS Sg gg g§ SS 2S 

cod dd d-j dd do d t> 

HH COCN rlrH (Mrt rlrH i-l 




o a 


* 










oo mm o o o r^ 


2S 


cnS 


—10c 00 or- o»co 010 t~T)< 

X I- C1H CROC HO T -T ^ i£5 


e d 










C-5 


<s 








r 8 


■s o 

|d 










I 2 


O 


2 




CO 




3 




TH 1 0C 


z 


10 





3 


fe 




























£2 






























2 " 


$ 


























- 


g SS 33 S8S 


Tfffl 


s§ 


S§ feg2 gg SS gg gg 


DID . 


B r-fi-i r-Jr^ 


^'t! 


coco 


CN CN tt'^ Oi O) dd r-ir-, Hr- 


gs 








!! 










e . o> 


CR 


UO 




^ 









co 


lO 





_^ 


CO 


§ 
















CO 




00 


CO 








p 


8 o 


* 


d 




d 




CO 




"* 


d 


~ ; 


d 


d 


d 




is 
ft, 




























3 S g 


«j °° 


00 


d 




s 












d 







CO 




S3 




d 


S^o 




























^c| 


Gs 




























s . 


r- CO CM CM CO ■* 


-f-O 


33 t~ 


10 ifi 


COM Ot- 0000 CMtH t^f 


11 


« coo t~o -sun 




COCO 




coco lO rH OlO OM or- 


g d co cm d -via 






C4-J t^Tl! dd r-5d t-^rH O t- 




53 COCM NH Ni-I 


CO C-l 






S-S 


6 


















ni 






,_ 






"2 






- 




y 




:■ 














i 




be . 


ojo : 

3 • 


c3 






§ 












C3 

to 




! 




3 




C3 




| 
































"O 




•d 




"O 














-d 




■0 : 


•0 : 




















5 












-a 




■a 






p 


















































a3 : 


c3 : 


^2 






— 






■°_ 






tT 




y 




t,- 




«3 




S3 






0) 

3 




a> • 


| i 


Ad" 

a 






a 






| 






X> 




3 




= 




1 




jjj 






,a 




■° : 


* • 


-d 






•a 






-z 






^T 




;M 




^>- 




•°. 




A 












J* ; 








CS 
























^ 








•d 


a 




1 : 


1 : 


jT 






S 






S 






s 




a 




5 




1 




a 




o 
































-d 




•d 












o 


•d 








si 






















= 




j3 




■d 
















CS • 


o> 























4) 








B) 




Si 




"o 


£ 




£ : 


z> '. 


— 






■g 






fl 






fl 




5 




5 




O 






■= 


.Q 




9) 1 


', 4> ! 






4 






7 






a 

cS 




a 




a 

si 








s 




M • 


5 
> 

J, 

CO 




2 : 
1 : 


^ : 


W 

1 






a 

w 

{ 






5 

4 






g 




& 

I 




s 





2 




1 




















































>■: 1 


! § 55 IS : 




■ 2 9 


ilz 


y§l3 


§ J5 S § * 2 < 


-' • C - '■ t 




= 7"= H~ = p~ = 3 


10 = a 


""5 r: 


T = =~'==~"==~^H"r'=HT = 












































0. ft ft p, 


<WB» 


•*-- i_ 


« - — i_- PP gW« gW -^-" i_- - 




X X X X 












W 




w 


W 


w 






Id 






w 






W 




H 




w 




K 




H 





62 



.- a 

it 
u 

o 
i? 



i 7 

— i- : 

m 

■I I 






; 



:. g 



r. :- / i- 



S - gjgsg - v 






8 g [S | 



I . 



:' •-;' i - — 



g S 8S3S 5 9 3S3SS 



II 



C K 



— :• ?i :i 






■SptO' 



'— - — S- 



~ ~: SJhXS 



|gig§ 






gsss 


V. 




- ? 1 1 - r i 






i-i - e i . 


5 oi ?i i-i 
C5 






e i -:' i - — 


- 


x 


?i ti ri ri 


s 


1 - 

X 


— S "7 9. 

ri — r ' — 


"SSS3 


% 


« 


T. 

I--TI- 


?. 


3 


— s". -2 .- 


- r , 


- 


.r. ^ n ~ 



-i -i cirinri ri n :i:i:i:i 



: i — r i -Z ~- — j i - 



■- ■- ■- / EC 



: i - r. r 

; .- ?l I- 



if. c / i - 
■d -r -r n 



S 7j^,i 2 * : 



bog « 



is s = llll 3 



^ : : = /" r — - i - ■• — 



o-;SSS It g gS! 



g-2 



"W eo o^..":fi i- — i •'■-.'/ ~. 



:::*.. 


_ 


_ 


; ; :<j 




• • ■ a 


IH 


- 


--- 1 


M 


111* 


A 

? 


— 


111% 

aaai 


— 

db 


««)jO 


S 


- 


a a a 3 


- 








a a = - 












> > -; H 

EX ;/ t; s> 

g c § g 


he 


:/ 


.^ .^ ,^_ v f 


i/ 


3 


i 


be bi be~ 


s 












£JE£ = 


= 


E 


355S 




































V 




.... 
















~r 




1) o> wo 














-~-r_ 


— 


— 


---_ 


— 


777; 


J 








i i i-i 


- 
J 


7 


xxx — 


- 








y.v.y/ 


: 
S3 




D 3 o5 


































aJajL 




a- 


saaa. 





: : — 


_ 






a 












£ 


- 






888* 


£ 


^ 


SS55 












i i J: = 


= 


d 








i: ? S 'J 


t/ 


i/ 


ta -< bee 


- 


- 


£=££ 












aaa . 
























- ~ -~ 


— 


— 


— — — _ 








X 


x 












- 








x x % x 


: 
2 


K 








a a a a 




r 


D 01 41 4) 


- 


- ; 



— — — 
aaa 



— — — 



t S.S.8g.8&8|g.S.S8 2i 

^-x-x— X— s s s s - s ■ 

mi H H Hfc — - 



> ^^^-^r ^^ — "r — — — 

_ 111 



63 

The results included in the above table are made use of elsewhere 
(p. 65) in discussing the true digestibility of the different sorts of 
bread studied. In general it va&y be said that, as shown b}- these 
experiments, a considerable part of the nitrogen in the feces was due 
to metabolic products rather than undigested residue, or, in other 
words, that the protein of the ration was quite thoroughly digested. 

ARTIFICIAL DIGESTION OF BREAD WITH PEPSIN. 

A report of earlier experiments-' carried on in the laboratory of the 
Maine Experiment Station contained an account of tests of the diges- 
tibilit}^ of the protein of bread made from different grades of flour by 
means of pepsin solution, in which was included a brief discussion of 
the Stutzer method for carrying on such work and the various modi- 
fications of this method which have been proposed from time to time. 
It is of course the purpose in artificial digestion experiments to approx- 
imate as closely as possible the conditions of heat, moisture, and fer- 
ment activity found in the animal body, but it is safe to say that the 
results obtained as } r et in the laboratory are generally regarded as of 
more importance relatively than absolutely. That is, such experi- 
ments are better fitted to show differences in the ease, the rapidity, or 
the thoroughness of digestion in a given time of two or more mate- 
rials treated in exactly similar ways than to indicate what would be 
the result when they were eaten, or the actual amount of nutrients 
which the same materials would supply to the body in their passage 
through the digestive tract. 

The tests reported in the following pages are similar in every way 
to the earlier work carried on in this laboratory, which was referred 
to above. Briefly, the method employed consisted of mixing 1 gram 
of finely ground "partially dry" bread with 200 cubic centimeters 
of pepsin solution prepared by dissolving 1.25 grams of German 
plain pepsin in 1 liter of 0.2 per cent hydrochloric acid. The pepsin 
solution containing the bread was kept on a water bath at 50-60 c C. 
for eight hours on two consecutive days, fresh hydrochloric acid being 
added every two hours. After standing over the night following 
the second day of heating, the clear supernatant liquid was decanted 
and the remainder filtered. The undissolved, that is, undigested, 
residue was dried, weighed, and its nitrogen content determined as 
usual. Deducting this amount of nitrogen from the amount origi- 
nally present in the bread gave the amount digested under the experi- 
mental conditions. The following table gives the results obtained 
when samples of breads made from entire-wheat. Graham, and white 
flours ground from the same lot of wheat were digested with pepsin 

« U. S. Dept. Agr., Office of Experiment stations Bui. 85. 



64 

solution, the breads used being the same as in digestion experiments 
with men, Nos. 431-402: 

Table 44. — Results of experiments on digestion of breads of different sorts with pepsin 

snlntinn. 





K'iinl of bread. 




Nitrogen. 




Sample 
number. 


[n bread. 


In undi- 
gested 
portion. 


In di- 
gested 
portion. 


dents of 
digesti- 
bility. 




White bread 


/v r <•' Hi. 
2. 16 
2.10 


Per ii at. 
0.06 
.12 


/•. r <•' nt. 
2. in 
i . 06 


l'i r it nl. 


6132 


do 












2.13 


.09 


2.04 










6143 


2.17 
2. 19 
2.04 


.13 
.08 
.07 


2.04 
2.10 

1.97 






.... do 




6145 


do 












2.13 


• .10 


2.04 










6156 


2.19 
2. '--J 


.10 

.1:: 


2.09 


95.43 


6157 


do 


'.<! 11 










2.20 


.11 


2.09 


94.79 








6195 


L98 


.09 
.01 


1.90 


96.49 


6196 


do 












1 . 99 


.06 


1.93 










6446 


2.31 
■1. 82 
2.82 


.05 

HI 


2.26 




6447 


do 




644S 


do 












2.32 


.OS 


2.27 










6471 


2.36 
2. 82 
2.30 


.07 

.n7 


2.29 
2.24 


97.03 


6472 


do 


95.00 


6473 


do 












2.33 


.07 


2.26 


97.00 








6493 


2.49 
2. 19 
2. 16 


.18 
.11 
.12 


2.31 
2.84 


92.77 


6494 
6495 


do 

do 


86. 12 




2.48 


.15 


2.33 










6632 


i^86~ 
1 B2 
i - 1 
L84 
1 . B6 
1.83 


.03 
.06 
.08 
.04 

.05 


1.83 
1.77 
1 BO 
1 90 
1 BO 
1.78 




6633 


....do 




CC34 


....do 




6673 


....<lo 




(KJ74 


....do 


87 80 


6675 


... .do 












1.84 


.04 


1.80 


97.73 




White bread 




6655 


1.67 
1.70 
1 . 67 
l 70 

1.71 


.05 
in 
.04 


1.62 
1.84 


'.<: 00 




do 




6657 


do 




6695 


do 






do 




6697 




87 "1 




,,,, 


.« 


1.64 


97.14 









From the figures in the above table it will be seen that the protein 
of bread made from straight patent, entire-wheat, or ( rraham Hour was 
quite thoroughly digested by the pepsin. The differences observed 

between the different sorts of bread were not great, yel on the whole 
it is evident that the protein of the Graham bread was somewhat less 

completely digested than that of the white or the entire-wheat bread. 



65 

As regards the two sorts last mentioned the differences noted are very 
small, although the advantage is with the white bread. These deduc- 
tions hold good whether the average results of all the tests are con- 
sidered or whether the results of individual pairs of tests are compared. 

COMPARISON OF COEFFICIENTS OF DIGESTIBILITY OF PROTEIN 
IN BREAD AS DETERMINED BY DIFFERENT METHODS. 

Table -±5 summarizes the coefficients of digestibility of the nitrogen 
(or protein) of breads made from different grades of flour, as shown 
by the results of both natural and artificial digestion experiments, 
including in the former case the results as actually determined and as . 
corrected for the nitrogen of metabolic products in the feces. As 
explained above, the feces were treated in two ways, with a ferment 
and with various solvents, to remove the metabolic products, and the 
nitrogen in the undissolved portion was considered in each case as per- 
taining to undigested residues of food. The table includes only the 
results for breads used in experiments Nos. 431-44:1, since these were 
the only ones of those here studied in which it was possible to esti- 
mate the digestibility of the protein of bread alone. 

Table 45. — Digestibility of nitrogen (or protein) of different kinds of bread as determined 
by different methods. 



Sample 
number. 



Kind of bread. 



Artificial 
digestion. 



Natural 
digestion 
■with cor- 
rection ob 



Natural 
digestion 
with cor- 
rection ob- 
tained bv 



■S5K- ass 

method. 



gj|o [White bread. 



6131 
6132 
6131 
6132 



6143 
6144 
6145 
6143 
6144 
6145 
6143 
6144 
6145 



..do 
..do 



Average of 3. 



■Entire-wheat bread 



do 

Average of 3 
[•Graham bread 



6166 I (lo 

6157 f— - flo 

6156 I 

6157 I 



Average of 3 



qH ^WMte bread. 



6195 

6196 



..... 



Average of 2. 



21675— No. 143—04— 



Pir rent. 
95. 72 



95.68 
94.95 



Per cent. 
94.71 



91.25 
95.49 



Pirn nt. Pur 






95. 45 


93. 52 


98. 39 


95.1 


96.35 


81.94 


95. 15 


M 


95. 58 


78. 72 


94.25 


87.35 


95. 67 


• "• 


94.75 


W 


95. 87 


8a bi 


n 


87. 11 


94.78 


80. 95 




88. 04 


94.86 


81.19 


94.25 


• 


" 


B1.60 


■ 


• ! 


95. 13 


81.25 


94. 34 




J 


85.16 


95. 95 


- 


96. 97 


77.21 


33.02 




97.01 


81.19 


91.49 


86. 12 



66 

As will be -ecu from a comparison of the data in the table, the 
largest coefficients for the white bread were those from the natural 
digestion experiments as corrected for the nitrogen of metabolic prod- 
ucts in the feces. Willi the other breads t 1m- results from the artificial 
experiments were highest, while those from the natural digestion 
experiments without the corrections were the lowest, [n the artifi- 
cial digestion experiments the pepsin solution used seemed to act with 
almost equal readiness upon the protein of all three kinds of bread, 

whereas iii the experiment- with men the protein of the white bread 

was more completely digested than that <>i either of the other kinds. 

These facts favor the idea often held that the apparently inc plete 

digestion of the coarse breads is due in part to their more rapid 
passage through the digestive tract. In the artificial digestion there 
is of course no such acceleration, the period of digestion being the 
same in all cases. 

INVESTIGATION OF METHODS FOR SEPARATION OF FECES. 

The success of a digestion experiment, unless i' he of longer dura- 
tion than is usually found practicable, must depend very largely upon 
the accuracy of the separation of the feces. Unless the experimenter 
is aide to distinguish with tolerable exactness between the feces from 
the food under investigation and feces from food taken immediately 
before and after the experiment, his work i- of little value. In some 
experiments, particularly those of the earlier investigators, the 
assumption was made that the feces of a given 'lay pertain to the food 
of the preceding day. Doubtless for healthy men of regular habits 
the period which elapses before the undigested portion of any given 
diet is excreted agrees in a general way with such an assumption, but 
the method is too indefinite for accurate experiment-. The method 
which ha- given most satisfactory results consists in imparting to the 
feces a particular color, or consistency, or both, t«> distinguish them 
from the feces of the preceding and following diets. It ha- Keen 
found that a diet consisting largely or wholly of milk produces iir,^ 
of a well-marked and individual character a- regards general color 
and consistency. Grape juice, blueberry juice, and similar material- 
impart a distinct color to the fece8. Charcoal and lampblack, which 
al-o give a distinct color to the \'m^. differ from vegetable coloring 
matter- in that they are not affected by the digestive juices, hut are 
excreted unchanged. Grape seeds, berry seeds, bits of string, etc, 
may he readily detected in the feces, and at time- have been used a- 

markers. 

Many investigators have reported data regarding the value of one 

or more method- of marking and separating \'<-ft-^. The literature of 
the-nhject ha- heen -tudied in connection with the experiments here- 
with, hut no attempt i- made t<> summarize the data here, a- it i- 



67 

believed that such a summary would be more appropriate when further 
investigations similar to those here reported have been carried out. 

Experience has shown that with the best means yet tried it is often 
difficult and sometimes impossible to make satisfactory separations of 
the feces. Methods that have been used successfully with one subject 
may prove failures with another or with the same subject at another 
time. 

The essentials of a good marker are as follows: (1) It must be of 
such a character that it can be unerringly detected in the feces. 

(2) It must be such that it will not to any appreciable extent disturb 
the secretion of the digestive juices or the regular action of the intes- 
tines: i. e., it must be neither constipating nor laxative in its effect. 

(3) It must not lag, but must move uniformly with the residues of the 
food with which it was ingested. (4) It .should not diffuse. 

The markers most commonly employed are of three general classes: 
(1) Foods producing feces of distinctive character, such as milk, 
grapes, grape juice, blueberries, etc. (2) Solid matter, not digestible, 
that will pass unchanged through the digestive tract, imparting a 
color, as lampblack, or which may be easily discovered, as knotted 
strings. (3) Composite markers, combining two or more of the above 
characteristics, as milk and lampblack. 

Of the various markers that have been employed at this station, 
milk accompanied by lampblack in many instances has proved satis- 
factory. Since milk feces are scanty, consisting perhaps more of 
metabolic products than of undigested matter, for the best results the 
milk should be given in large quantities unmixed with other food. 
The resulting feces from such a meal are very smooth, pasty, and tena- 
cious, and when well localized are very satisfactory as a marker. In 
the earlier digestion experiments at this station very good results were 
thus obtained: but in some of the later work both milk feces and 
marker were found so incorporated with the feces from the preceding 
and the following food that it was thought advisable to try other 
methods. An objection to the use of milk was found in the undesir- 
able constipating effect it frequently produces. In several trials 
lampblack given with the ordinary food proved as satisfactory as wheu 
used with milk alone. 

Grapes and raisins were found unreliable, the seeds sometimes pre- 
ceding and sometimes lagging far behind the feces they were supposed 
to accompany. Grape juice was tried with two subjects, and in one 
case its laxative effect was so pronounced as to preclude its use a- a 
marker. With the other subject the effect was equally decided but of 
quite the opposite character, the subject, although previously regular 
at stool, becoming very constipated. 

Some of the more striking results obtained up to the present time 
( L903) are given hare. Many ether experiment- of a similar nature have 
been made, with results in harmony with and confirming those mentioned 



«8 



LAMPBLACK AS A MARKER. 



Much of the difficulty encountered in attempts to mark feces with 
lampblack has been due to the wide distribution of the color through 
the feces, which is undoubtedly effected by the muscular contractions 

of the stomach and intestines. 

A very convenient method of administering the lampblack and one 
which has been generally followed in the nutrition investigations of 
which the present secies forms a part, is to inclose it in gelatin capsules 

about 0.T5 inch long and 0.3 inch in diameter. Since these capsules 
are readily soluble in water, they are doubtless ruptured in a Bhort 
time after they enter the stomach, and it ivas thought that diffusion 
might he largely prevented by delaying as long as possible the per- 
foration or solution of the capsule and the consequent liberation of 
the lampblack. 

To test this, ten tests were made with two subjects, E, a student, and 
M, a chemist, both healthy young men. the marker in cadi case being a 
gelatin capsule filled with lampblack, taken in seven tests with a meal of 
either milk or eggs alone, and in three with ordinary mixed diet. In 
the first four experiments the capsules were untreated, but in the other 
six thej' were doubly coated with shellac, which it was believed would 
render them less easily soluble and hinder the liberation of the lamp- 
black. The feces were deposited on tin trays which were slowly 
moved along so as to secure the feces in a straight line, thus facilitating 
the examination of them. The results of the tests were a- follows: 

Table 46. — Results of testa with lampblack as a marker for feces. 



"Sf ^^S 01 Distribution of lampblack. «?££*£& 



means of color. 



CAPSULE UNTREATED. 

Experiment No. 1, subject E... 
Experiment No. ■-'. subject E... 
Experiment No. ■'•, subject M .. 
Experiment No. 4. subject M .. 



Experiment No. 5, subject M .. 
Experiment No. •;. subiecl B... 
Experiment No. ". subiect E... 
Experiment No. 8, subject E... 
Experiment No. '.•. subject M .. 
Experiment No. 10, subject M.. 



Suppei 

do 

do 

do 



Milk — Very widely diffused... 

....do... Widelj diffused 

Eggs Somewhat diffused 

do ... Localized 



Suppei Mixed . 

do Milk... 

Breakfasl do .. 

do do .. 



Difficult 
Impossible. 
Moderate]) good. 

I'M. 



Somewhat diffused Fair. 

Localized, but in streaks. Difficult 

Localised % . .. Fair. 

Localized in streaks Poor. 



.do Mixed.. Localized in nodules 



.do. 



.do. 



.do 



Do. 



With the subject E the milk supper had little if any effect in secur- 
ing a more decided separation of the U'i-i-s. since the milk feee- were 
in each case more or less intimately mixed with the adjacent feces 
from other foods. With the subject M the marked meal consisted of 
eggs or was made ii]i of a number of food-, and the separations were 
more satisfactory. 

It was noted repeatedly that the lampblack used as a marker, together 
with more or less of the feces colored by it. lagged behind: that is, 



69 

fecal matter pertaining to food of a later meal preceded it in excretion. 
In many cases the color was found well localized in the feces, but the 
colored portion lay on one side of the center, as though that part of 
the feces had adhered to one side of the intestines while the undigested 
remnants of later food had been pushed by. In later experiments such 
a condition was apparently avoided, but with no gain in accuracy of 
separation, by the use of larger amounts of lampblack, which resulted 
in a wider diffusion of the color. Somewhat similar cases of lagging 
were noted in which several segments of the feces were thoroughly 
blackened on the exterior while within they were normal in color, 
and this when the main body of the blackened feces had passed by. In 
such cases there seemed to have been a telescoping of the intestinal 
contents, the central portions being forced through and beyond the 
outer ones. 

Where diffusion of the lampblack occurred it was usually observed 
that the first limit of the blackened feces was much more sharply 
denned than the last. In the later work, therefore, the method of 
separation by means of a prefatory and supplementary meal of milk 
accompanied by a capsule of lampblack, which, as previously stated, was 
followed in the earlier investigations of this Department, was aban- 
doned, and the lampblack was given with the regular breakfast of the 
first day of the experiment proper and with the breakfast of the day 
following the last one of the experiment. In making the separations 
of the feces, that blackened by the first lampblack was retained as 
belonging to the experiment, while that colored by the lampblack 
given after the close of the experiment was discarded. This is in 
harmon}' with the results of tests reported by Sherman in a recent 
bulletin, in which lampblack was taken with the breakfast of experi- 
ments succeeding one another without interruption, rather than with 
the supper preceding, since, as stated by Sherman. "It is very much 
easier to determine the point which marks the first appearance of the 
feces from a meal with which lampblack has been taken than to decide 
exactly where the feces from such a meal end: apparently because, as 
would be expected, enough lampblack may sometimes adhere to the 
walls of the intestines to give more or less color to the feces from 
meals subsequent to that with which it was taken." 

ACTION OF PEPSIN UPON TREATED GELATIN CAPSTTLES. 

Several methods were tried for retarding the solution of the gelatin 
capsules in the stomach. Mention has already been made of coating 
them with shellac. The effect of this procedure, and of treating 
the capsules with tannin and with formaldehyde, was studied by 
noting the action of pepsin solution upon capsules thus treated. A 

«U. s. Dept. Agr., Office of Experiment statiMii> Bui. 121. 



70 

number of capsules were filled with quartz sand and powdered cochi- 
neal the former to increase the specific gravity and secure more com- 
plete submergence of the capsule in the digestive fluid, and the latter 
to communicate its color to the solution and thus indi< ate the perfora- 
tion of the capsule. 

In these tests 1" capsules were used, as follow-: Nos. 1 and 2 were 
given a single coating of shellac; Nos. 3 and 4 were doubly coated with 
shellac; Nos. 5 and 6 were immersed two minutes in a strong solution 
of tannin and then dried; Nos. 7 and 8 were not treated, and Nos. '•' 
and LO were kept live minutes in a 20 per cent solution of formalde- 
hyde and then dried. Each of these capsules except No. 8 was placed 
in a separate beaker containing LOO cubic centimeters of pepsin solu- 
tion prepared as described above, that had been previously warmed to 
4o C, and was maintained at that temperature until the liquid was 
colored by the cochineal. As a control test No. 8 was kept in pure 
water at the same temperature. 

('apsides Nos. 1 and 2, which had the single coating of shellac, were 
ruptured or perforated in 30 minutes, so that the cochineal colored tin- 
liquid: Nos. ?> and 4, with the double coating of shellac, in To minutes; 
NO. 5, treated with tannin, in 7 minutes 30 second.-: No. •'.. also treated 
with tannin, in 5 minutes; No. 7. not treated, in 3 minute-: and No. s . 
the duplicate of No. 7. which was kept in warm water, also in 3 minutes. 
Nos. d and 10, which had been treated with formaldehyde, showed the 
greatest resistance to the action of the pepsin. After 4 hours of con- 
tinuous digestion, although the gelatin had become much softened, 
a mere trace of the cochineal had passed into the solution; and while 
after 2 hours' further digestion the color had deepened greatly, the 
capsules still retained their form. From what has been observed in 
our experiments with men it seems certain that in the alimentary canal 
all of these capsules would have been ruptured in less time than in these 
tests with pepsin solution. 

Coating the capsule with shellac, as shown by the tests, retarded the 
solution of the gelatin, and in the tests with men it decreased the 
tendency toward a diffusion of the charcoal. It can not be inferred 
from this, however, that the coated capsules would give more accurate 
results in digestion experiments with men than the uncoated. < >n the 
coni rary, there i- reason to believe thai a capsule before disintegration 
is more subject to displacement than are it- content- when thoroughly 
incorporated with the \'n-c^. 

KNOTTED STRINGS AS MARKERS. 

Two experiments, extending through several weeks, were made with 
knotted strings as markers for feces. A loosely twisted, -oft. white 

cotton -tring. such as i- used for tying -mall parcel-, was chosen for 
the purpose, iii the belief that it would prove less irritating to tin 1 



71 

intestine than hard twine. ^Vith each meal a piece about 1.5 inches 
long was swallowed. Generally, in the string taken with breakfast, 
one knot was tied, two in that with dinner, and three in that with 
supper; but from time to time, in order that the strings of one day 
might not be mistaken for those of another, a departure was made 
from this rule, four knots being used to indicate breakfast and two 
and three knots at varying distances to mark the other meals. The 
diet was simple but generous. The subject was a man whose duties 
required considerable activity. He defecated once nearly every day 
during the experiments, taking care that the feces were deposited in 
such a wa} T that the order of the discharge of the strings could be 
accurately determined. 

The results of the experiments are shown in the following table, 
which gives the meals taken, the time of discharge of the feces, the 
order of ingestion of the strings, the order of their discharge, and the 
length of the period between ingestion and discharge: 

Table 47. — Relative movement of string markers in their passage tlirough the alimentary 

canal. 



Date of ingestion. 



Order 
of inges- 
tion. 



Time of defecation. 



Number Period 

and order between 

of strings ingestion 

in the and dis- 

feces. charge. 



FIRST SERIES. 



Saturday, April 2S: 

Morning 

Noon 

Night 

Sunday. April 29: 

Morning 

Noon 

Night 

Monday. April SO: 

Morning 

Noon 

Nisht 

Tuesday. May 1: 

Morning 

Noon 

Nisrht 

Wednesday, May 2: 

Morning 

Noon 

Night 

Thursday. May 3: 

Morning 

Noon 

Night 

Friday, May 4: 

Morning 

Noon 

Night 

Saturday, May 5: 

Morning 

Noon . .' 

Night '.. 

Sunday. May &. 

Morning 

Noon 

Night 

Monday, May 7: 

Morning 

Noon 

Night 



Saturday. April 28 

Sunday, April 29: 
9 a.m 

Monday, April 30: 
Noon 

Tuesday, May 1: 
4 p. m 

Wednesday, May ! 



Noon 

Thursday, May 3: 

3p.m 

Friday, May -i: 

4 p.m 

Saturday, May 5: 

4 p.m 

Sunday, May 6: 
4 p. in 

Monday. May 7: 



! i 


46 
33 


( .5 
1 S 


42 
24 

18 

24 


: :i 


32 
21 


l 14 

\ 16-17 
1 18 


52 

33-28 


\ 20 


33 
22 
28 


! 1 


33 
28 


25 

-- 


- 
10 



i ! 



Feces from experiment did not appear. 



:•_> 



Table 4; 



■RelatiiM movement of string markers in their passagt through tht alimentary 
canal— t iontinued. 



Night 

Monday, May 21: 

Morning 

Noon 

Night 

Tuesday, May 22: 

Morning 

Noon 

Night 



Wednesday, May 2 

Morning 

Noon 

Night 

Thursday, May 24: 

Morning 

Noon 

Night 



L8 

Monday, May 21: 
19 No 

20 



Tuesday, May 22: 



Wednesday, May 

No '■ 



Thursday, May 24: 

i p. in 



Date of ingestion. 


Order 

Hull. 


Time "i defecation. 


Number Period 

md order 

in tin- and dis- 
charge. 


first beeie — continued. 

May 8: 


:-:i 
82 
33 

:;i 

87 

38 

:::> 

40 
4] 
42 

11 
45 

.. i.; 

17 

" 1^ 

1 
3 

4 

s 

6 

8 
9 

10 
11 
12 

18 

14 
15 

if. 
17 


'lu. -day. May B: 

Wednesday, May 9: 


1 g 

1 S 

! i 

11 

11 

1 ■• 












W sdnesday, May 9; 




Noon 






Thursday, May 10: 




Thursday, May 10: 


• 




Friday. May 11: 

8p.m . 

Saturday, May 12: 

1 i'. m 

Sunday, Maj 18: 

lOp.m 

Tuesday, May 15.6 
Wednesday, May IB: 








Friday, May 11: 












Saturday. May 12: 








Night 




Sunday, May 13: 












BE) OND SERIES. 

Tuesday, May 15: 


16 






Night 




Wednesday, May 16: 








Night 


Thursday, May 17: 

I p. m 

Friday. May 18: 
No 6 

Saturday. May 19: 




Thursday, May it: 












Friday. May 18: 








Night 




Saturday. May 19: 








Night 




Sunday. May 20: 


Sunday, v 

Noon 


M 
1- 


N ■ M >ll 





18 




17 






.'I 


1- 




21 


U 


19 





■< i",,-.- containing these ^trinu'> not collected. '• Feces from experiment did not appear. 



73 

Table 47. — Relative movement of string markers in their passage through the alimentary 
canal — Continued. 



Date of ingestion. 



Order 
of inges- 
tion. 



Time of delectation. 



Number Period 

and order between 

of strings ingestion 

in the and dis- 

feces. charge. 



second series— continued. 



Friday, May 25: 
Morning ... 

Noon 

Night 



Saturday, May 26: 

Morning 

Noon 

Night 

Sunday. May 2, : 

Morning 

Noon 

Night 



Monday. May :>: 

Morning 

Noon 

Night 

Tuesday, May 29: 

Morning 

Noon 

Night 

Wednesday, May 

Morning 

Noon 

Night 



Thursday. May 31: 

Morning . . 

Noon 

Night 

Friday, June 1: 

Morning 

Noon 

Night 

Saturday, June 2: 

Morning 

Noon 

Night 



Sunday, June 3: 

Morning 

Noon 

Night 

Monday, June 4: 

Mi lining 

Noon 

Night 



Friday, May 25: 
11 a. m 



Saturday, May 26: 

lp-m 

Sunday, May 27: 

3 p. m 

Monday, May 28: 

1 p. m 

Tuesday, May 29: 

•1 p. m 

Wednesday, Mav J 



1 p. m 



Thursday, May 31: 
5 p. m 

Friday. June 1: 
3 p. ni 

Saturday. June 2: 



3 p. m 



Sunday, June 3: 

5 p. m 

Monday, June 4: 



57 


42 


56 


48 


60 


1- 


59 


24 


58 


29 



a No strings taken. 

The first experiment as a whole covered 16 days, the data in the 
table above showing the order of ingestion and discharge of 45 
strings. The time which elapsed between the ingestion and the appear- 
ance of a string in the feces varied in different instances from L0 to 52 
hours, the average being about 29 hours. In only five tests did the 
markers appear in the feces in the same order as that in which they 
were taken with tlie food. In seven cases there was a simple trans- 
position; that is. the string from one meal appeared before that ^\ the 
meal next following. For instance, in the feces on April 30 the string 
taken with dinner on April l".» preceded that taken with breakfast on 



74 

the same day. More complex transpositions occurred on May 7 and 
12. Murker No. 24, which appeared on the former date, was not dis- 
charged until 47 hours after its ingestion, and was preceded by three 
strings taken with later meals, one of which. No. 28, required only 10 
hours from ingestion to discharge. In several cases, as with strings 
Nos. 16 and 17. two markers were so located in the feces that neither 
could be given priority. 

The number of markers appearing at each discharge of feces 
varied from 2 to .">. The discharge on May 9 was the first for two 
days, and the extra number was to be expected. Likewise, of the five 
markers discharged May 7. one had lagged from May 5. But why 
No. 28 should have appeared 10 hours after ingestion is not clear, since 
the feces were apparently perfectly normal, though they were retained 
until a later hour than usual. The subject had been engaged during 
the afternoon in rather hard work. 

The second experiment continued for a longer period — 21 days, on 
the Last of which no strings were given. The results were perhaps 
even more striking than those just noted. While the markers were 
given regularly, in only eight tests did they appear in the feces in the 
same order as that in which they were taken. In twelve instances 
the string given with one meal appeared before that of the meal imme- 
diately preceding; and twice, namely, on May 22 and June 4. the order 
of the discharge of the strings for three succeeding meal- was the 
reverse of that of their ingestion, the one given with breakfast being 
discharged last and that with .-upper of the same day appearing first. 
The period of longest retention was 57 hours, but on rive other occa- 
sions the period exceeded 50 hours. The shortest period was 17 hours, 
and the average for the 60 markers was a little over 33 hours. 

Considering the two experiments as a whole 108 markers were used. 
35 of which, or about one-third of the total number, in the passage 
through the alimentary canal overtook and passed markers that had 
been taken before them. Only 44 strings, or 4<> per cent of the total 
number, accomplished the passage and were excreted in the order 
in which they were taken. 

In all probability all the strings left the stomach and entered the 
intestines in the order in which they were ingested. In that case the 
transposition took place in the intestines; whether in the small or large 
intestine or in the rectum immediately before expulsion is immaterial 
so far as concerns the present discussion. 

Although the subject of these experiments was a strong, healthy 
man. it may be that after all the conditions were not strictly normal, 
since the kind of work he performed may have had some influence 
upon the results. It is quite conceivable that retention of the feces 
beyond the regular time of discharge might result in a more complete 
mixing of the intestinal contents. Nevertheless the work shows the 



75 

unreliability of string markers, and to a greater or less degree of 
markers in general. All matter evidently does not pass through the 
intestines in the order in which the food is ingested. 

In some of the most pronounced cases of lagging the strings were 
found in the feces in positions that indicated that they must have been 
in contact with the walls of the intestine, so that their forward move- 
ment was retarded by friction. This is similar to the phenomenon 
that was repeatedly observed in experiments in which lampblack was 
used, as noted on page - 

That the intestinal walls are able to change the position at least of 
irritating bodies is shown by the results of experiments carried on by 
A. Exner' 7 with dogs and cats fed pieces of glass and pins inclosed in 
gelatin capsules. It was found that the position of the objects was 
quite generally changed in their passage through the intestinal tract 
so that the sharp points did not come in contact with the intestinal 
walls. In proof of this it was noted that by far the larger number of 
pins were excreted head first, whether they were swallowed in this 
way or not. 

It is quite probable that the displacement of the knotted strings in 
the experiments carried on at the Maine Station was accidental, as it 
hardly seems probable that the knots would prove irritating enough 
to the intestinal walls to cause a change in position of the same char- 
acter as that observed by Exner. but until more evidence is available 
it can not be said with certainty that the susceptibility of the intestinal 
walls to irritating substances was not a factor in the change of position 
of the knotted strings. 

SUMMARY OF EXPERIMENTS WITH MARKERS. 

None of the markers thus far tried have fully met the conditions 
previously noted as essential. 

Solid markers, like strings and grape or tig seeds, although possessing 
the virtue of easy detection in the feces, are subject to considerable 
displacement, and may be found far from the portion of the feces that 
they were intended to mark. Finely divided, insoluble matter, such. 
as lampblack, though less likely to be displaced than the coarse mate- 
rial, frequently becomes so diffused as to be useless as a marker, the 
color passing by imperceptible gradations into the normal. Methods 
which prevent diffusion of color do not necessarily insure accuracy of 
separation. 

The first appearance of a color marker is more sharply defined than 
the last. 

Foods, such as milk or Graham bread, which produce characteristic 
feces, may also fail, through diffusion, to insure an accurate separation. 

^Arch. Physiol. [Pflugerj. 89 (1902), p. 253. 



76 

While many of these markers may give, and in many cases have 
given, satisfactory results, the percentage of failures is large. 

Markers which prove satisfactory with one subject may fail with 
another, or with the same subject in another experiment. 

In digestion experiments reliable results can be hoped for only when 
the experimental period is fairly Long, at least four days, and the 
subjects are of regular habits. Regularity i- a matter of the greatest 
importance, since feces can rarely be so marked that separations can 
safely be made by color alone. Increased accuracy may be obtained 
when evacuations take place daily and at about the same hour. Reten- 
tion of the intestinal contents beyond the usual period appears often 
to result in greater displacement of different portionsof the feces than 
would otherwise be likely. 

While too great reliance should not be placed on a marker of any 
kind, as shown by the results of a large number of experiments, 
lampblack, when properly used, has given tolerably good results, and 
may be considered a valuable aid in the separation of feces. The 
texture of the feces and the time of their appearance (if the subject 
be of regular habits) are factors which must be considered of equally 
great importance. 

METHOD ADOPTED FOR DIGESTION EXPERIMENTS WITH MEN. 

As a result of the studies with markers which have been reported 
and the experience gained in previous experiments, the following 
method for digestion experiments with men has ben adopted in the 
work at this station: 

Digestion experiments are made for periods of not less than four 
days. When condition.- permit, the supper preceding the firs! meal of 
the experiment consists of food yielding feces of a texture different 
from that of feces from the food used in the experiment. A -ingle 
untreated gelatin capsule tilled with lampblack i- taken with the break- 
fast of the first day. and a similar capsule with the breakfast of the 
day following the last one of the experiment, this meal, like the one 
preceding the experiment, being preferably of food different from that 
used in the experiment. If the color is well localized the separation 
i- usually easy, the first lot of colored U'>-<-- being included in that 
reserved for analysis, while the colored \'*-<-*^ pertaining to the break- 
fast following the last meal are rejected. The texture <»f the \'<-c,-~ 
i- also carefully noted. If. a- sometimes happens, a portion of the 

fe,,- thus collected appear- to have been mixed with that from other 
food.-, the different parts are mechanically separated according to the 

general appearance of the feces, and the portion not pertaining to 
the diet studied i- rejected. An examination of the feces outside the 
limit- defined by the marker- sometimes -how- -mall a nut- from 



77 

the food under investigation which must also be mechanically separated 
and included with that for analysis. Such mechanical separation of 
the different parts of the feces may be readily made with a spatula, 
and when done under a hood with a good draft need not be especially 
disagreeable. 

Special pains are taken to impress upon the subject the importance 
of the utmost regularity, particularly as to the time of evacuation. 
The subject is also cautioned against a too radical change of diet after 
the experimental period is ended. Too free indulgence in fruits at 
the close of the experiment and before the appearance of the second 
marker is particularly to be avoided, since the laxative effect of such 
food may render a satisfactory final separation impossible. A four- 
day experiment may be made worthless by failure to observe a few 
simple precautions of this kind. It must be remembered that the 
experiment is not finished and vigilance should not be relaxed until 
the second marker has appeared and the final separation is made. 







A 



<* 



LtMr'07 






